B lymphocytes Lymphocytes Lymphocytes are heterogeneous WBCs involved in immune response. Lymphocytes develop from the bone marrow, starting from hematopoietic stem cells (HSCs) and progressing to common lymphoid progenitors (CLPs). B and T lymphocytes and natural killer (NK) cells arise from the lineage. Lymphocytes: Histology, also known as B cells, are important components of the adaptive immune system Immune system The body's defense mechanism against foreign organisms or substances and deviant native cells. It includes the humoral immune response and the cell-mediated response and consists of a complex of interrelated cellular, molecular, and genetic components. Primary Lymphatic Organs. In the bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types marrow, the hematopoietic stem cells Hematopoietic stem cells Progenitor cells from which all blood cells derived. They are found primarily in the bone marrow and also in small numbers in the peripheral blood. Bone Marrow: Composition and Hematopoiesis go through a series of steps to become mature naive B cells. The cells migrate to secondary lymphoid organs Lymphoid organs A system of organs and tissues that process and transport immune cells and lymph. Primary Lymphatic Organs for activation and further maturation. The process entails antigen Antigen Substances that are recognized by the immune system and induce an immune reaction. Vaccination stimulation, with or without the help of T cells T cells Lymphocytes responsible for cell-mediated immunity. Two types have been identified - cytotoxic (t-lymphocytes, cytotoxic) and helper T-lymphocytes (t-lymphocytes, helper-inducer). They are formed when lymphocytes circulate through the thymus gland and differentiate to thymocytes. When exposed to an antigen, they divide rapidly and produce large numbers of new T cells sensitized to that antigen. T cells: Types and Functions. The T-cell–independent activation generates a short-lived immune response (via plasma Plasma The residual portion of blood that is left after removal of blood cells by centrifugation without prior blood coagulation. Transfusion Products cells), and this is seen with antigens such as bacterial lipopolysaccharides Lipopolysaccharides Lipid-containing polysaccharides which are endotoxins and important group-specific antigens. They are often derived from the cell wall of gram-negative bacteria and induce immunoglobulin secretion. The lipopolysaccharide molecule consists of three parts: lipid a, core polysaccharide, and o-specific chains (o antigens). When derived from Escherichia coli, lipopolysaccharides serve as polyclonal b-cell mitogens commonly used in laboratory immunology. Diarrheagenic E. coli. T-cell–dependent activation, on the other hand Hand The hand constitutes the distal part of the upper limb and provides the fine, precise movements needed in activities of daily living. It consists of 5 metacarpal bones and 14 phalanges, as well as numerous muscles innervated by the median and ulnar nerves. Hand: Anatomy, produces both plasma Plasma The residual portion of blood that is left after removal of blood cells by centrifugation without prior blood coagulation. Transfusion Products cells and memory cells Memory cells Cells that outlived a previous infection Adaptive Immune Response. Activated B cells Activated B cells Humoral Adaptive Immunity then proliferate in the germinal centers, but not all become effector B cells. Through somatic hypermutation, B cells undergo additional mechanisms to increase the affinity of the antibody to the antigen Antigen Substances that are recognized by the immune system and induce an immune reaction. Vaccination. Only those with high-affinity B-cell receptors Receptors Receptors are proteins located either on the surface of or within a cell that can bind to signaling molecules known as ligands (e.g., hormones) and cause some type of response within the cell. Receptors subsequently advance for terminal differentiation. B cells then go through class switching (from IgM IgM A class of immunoglobulin bearing mu chains (immunoglobulin mu-chains). Igm can fix complement. The name comes from its high molecular weight and originally being called a macroglobulin. Immunoglobulins: Types and Functions to another class of Ig Ig X-linked Agammaglobulinemia) under the influence of cytokines Cytokines Non-antibody proteins secreted by inflammatory leukocytes and some non-leukocytic cells, that act as intercellular mediators. They differ from classical hormones in that they are produced by a number of tissue or cell types rather than by specialized glands. They generally act locally in a paracrine or autocrine rather than endocrine manner. Adaptive Immune Response. After class switching, the B cells become plasma Plasma The residual portion of blood that is left after removal of blood cells by centrifugation without prior blood coagulation. Transfusion Products cells (which produce antibodies Antibodies Immunoglobulins (Igs), also known as antibodies, are glycoprotein molecules produced by plasma cells that act in immune responses by recognizing and binding particular antigens. The various Ig classes are IgG (the most abundant), IgM, IgE, IgD, and IgA, which differ in their biologic features, structure, target specificity, and distribution. Immunoglobulins: Types and Functions) or memory cells Memory cells Cells that outlived a previous infection Adaptive Immune Response (which mount a robust secondary immune response Secondary immune response Humoral Adaptive Immunity).
Last updated: 10 Mar, 2022
B (bursa-derived) lymphocytes Lymphocytes Lymphocytes are heterogeneous WBCs involved in immune response. Lymphocytes develop from the bone marrow, starting from hematopoietic stem cells (HSCs) and progressing to common lymphoid progenitors (CLPs). B and T lymphocytes and natural killer (NK) cells arise from the lineage. Lymphocytes: Histology, or B cells, are a type of lymphocyte that arises from the common lymphoid progenitor.
The B-cell
receptor
Receptor
Receptors are proteins located either on the surface of or within a cell that can bind to signaling molecules known as ligands (e.g., hormones) and cause some type of response within the cell.
Receptors (
BCR
BCR
Lymphocytes: Histology) consists of the
Ig
Ig
X-linked Agammaglobulinemia molecule and the signaling molecule:
Ig
Ig
X-linked Agammaglobulinemia contains 2 identical
heavy chains
Heavy chains
The largest of polypeptide chains comprising immunoglobulins. They contain 450 to 600 amino acid residues per chain, and have molecular weights of 51-72 kda.
Immunoglobulins: Types and Functions and 2 identical
light chains
Light chains
Polypeptide chains, consisting of 211 to 217 amino acid residues and having a molecular weight of approximately 22 kda. There are two major types of light chains, kappa and lambda. Two ig light chains and two ig heavy chains (immunoglobulin heavy chains) make one immunoglobulin molecule.
Immunoglobulins: Types and Functions linked by a disulfide bridge. The membrane-bound
Ig
Ig
X-linked Agammaglobulinemia is anchored to the cell surface.
To reach functionality, the B cell goes through stages in the bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types marrow and the secondary lymphoid organs Lymphoid organs A system of organs and tissues that process and transport immune cells and lymph. Primary Lymphatic Organs:
Maturation stage | Ig Ig X-linked Agammaglobulinemia genes Genes A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. DNA Types and Structure | B-cell receptor Receptor Receptors are proteins located either on the surface of or within a cell that can bind to signaling molecules known as ligands (e.g., hormones) and cause some type of response within the cell. Receptors ( BCR BCR Lymphocytes: Histology) | Associated events |
---|---|---|---|
Antigen Antigen Substances that are recognized by the immune system and induce an immune reaction. Vaccination-independent | |||
Pre-pro-B cell Pre-pro-B cell Lymphocytes: Histology | Germ-line DNA DNA A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine). DNA Types and Structure | None | No heavy- or light-chain expression |
Pro-B cell Pro-B cell Lymphocytes: Histology | IGH D-J rearranged | None | Starts to express CD19, CD34, and HLA-DR (class II histocompatibility antigen Antigen Substances that are recognized by the immune system and induce an immune reaction. Vaccination) |
Pre-B cell | IGH V-D-J rearranged | Pre-
BCR
BCR
Lymphocytes: Histology is formed:
|
Other markers appear (CD79, CD10, CD20, CD40 CD40 Members of the tumor necrosis factor receptor superfamily with specificity for CD40 ligand. They are found on mature B-lymphocytes, some epithelial cells; and lymphoid dendritic cells. Evidence suggests that CD40-dependent activation of B-cells is important for generation of memory B-cells within the germinal centers. Mutations in the CD40 antigen gene result in hyper-igm immunodeficiency syndrome, type 3. Signaling of the receptor occurs through its association with tnf receptor-associated factors. Hyper-IgM Syndrome, and terminal deoxynucleotidyl transferase Terminal deoxynucleotidyl transferase A non-template-directed DNA polymerase normally found in vertebrate thymus and bone marrow. It catalyzes the elongation of oligo- or polydeoxynucleotide chains and is widely used as a tool in the differential diagnosis of acute leukemias in man. Acute Lymphoblastic Leukemia among them). |
Immature B cell Immature B cell Lymphocytes: Histology |
|
Mature BCR BCR Lymphocytes: Histology ( IgM IgM A class of immunoglobulin bearing mu chains (immunoglobulin mu-chains). Igm can fix complement. The name comes from its high molecular weight and originally being called a macroglobulin. Immunoglobulins: Types and Functions molecule) | HLA-DR, CD19, CD20, and CD40 CD40 Members of the tumor necrosis factor receptor superfamily with specificity for CD40 ligand. They are found on mature B-lymphocytes, some epithelial cells; and lymphoid dendritic cells. Evidence suggests that CD40-dependent activation of B-cells is important for generation of memory B-cells within the germinal centers. Mutations in the CD40 antigen gene result in hyper-igm immunodeficiency syndrome, type 3. Signaling of the receptor occurs through its association with tnf receptor-associated factors. Hyper-IgM Syndrome expression continues, but not the other markers (e.g., CD10, CD34, and terminal deoxynucleotidyl transferase Terminal deoxynucleotidyl transferase A non-template-directed DNA polymerase normally found in vertebrate thymus and bone marrow. It catalyzes the elongation of oligo- or polydeoxynucleotide chains and is widely used as a tool in the differential diagnosis of acute leukemias in man. Acute Lymphoblastic Leukemia). |
Mature B cell Mature B cell Lymphocytes: Histology (naive) |
|
With mature BCR BCR Lymphocytes: Histology ( IgM IgM A class of immunoglobulin bearing mu chains (immunoglobulin mu-chains). Igm can fix complement. The name comes from its high molecular weight and originally being called a macroglobulin. Immunoglobulins: Types and Functions) → exit bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types marrow | All express CD19 and CD20. |
Antigen Antigen Substances that are recognized by the immune system and induce an immune reaction. Vaccination-dependent | |||
Mature B cell Mature B cell Lymphocytes: Histology (in secondary lymphoid tissues) | Mature BCR BCR Lymphocytes: Histology (expresses IgM IgM A class of immunoglobulin bearing mu chains (immunoglobulin mu-chains). Igm can fix complement. The name comes from its high molecular weight and originally being called a macroglobulin. Immunoglobulins: Types and Functions and IgD IgD An immunoglobulin which accounts for less than 1% of plasma immunoglobulin. It is found on the membrane of many circulating B lymphocytes. Immunoglobulins: Types and Functions once within the secondary lymphoid tissues) | Cells can rest or B-cell activation can occur: B cells interact with exogenous antigen Antigen Substances that are recognized by the immune system and induce an immune reaction. Vaccination and/or T helper cells. | |
Activated B cell Activated B cell Lymphocytes: Histology | Class switching | Once activated, can switch to IgE IgE An immunoglobulin associated with mast cells. Overexpression has been associated with allergic hypersensitivity. Immunoglobulins: Types and Functions, IgG IgG The major immunoglobulin isotype class in normal human serum. There are several isotype subclasses of igg, for example, igg1, igg2a, and igg2b. Hypersensitivity Pneumonitis, IgA IgA Represents 15-20% of the human serum immunoglobulins, mostly as the 4-chain polymer in humans or dimer in other mammals. Secretory iga is the main immunoglobulin in secretions. Immunoglobulins: Types and Functions, or remain as IgM IgM A class of immunoglobulin bearing mu chains (immunoglobulin mu-chains). Igm can fix complement. The name comes from its high molecular weight and originally being called a macroglobulin. Immunoglobulins: Types and Functions | |
Memory Memory Complex mental function having four distinct phases: (1) memorizing or learning, (2) retention, (3) recall, and (4) recognition. Clinically, it is usually subdivided into immediate, recent, and remote memory. Psychiatric Assessment B cell |
|
||
Plasma cell Plasma cell Specialized forms of antibody-producing B-lymphocytes. They synthesize and secrete immunoglobulin. They are found only in lymphoid organs and at sites of immune responses and normally do not circulate in the blood or lymph. Lymphocytes: Histology |
|
Differentiation stages of the B cell:
In
antigen
Antigen
Substances that are recognized by the immune system and induce an immune reaction.
Vaccination-independent stages, B-cell production starts with the hematopoietic stem cell (HSC), which becomes a common lymphoid progenitor (CLP) and then a
pre-pro-B cell
Pre-pro-B cell
Lymphocytes: Histology or B-progenitor cell. The next steps include
gene
Gene
A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms.
Basic Terms of Genetics rearrangement to assemble the
Ig
Ig
X-linked Agammaglobulinemia molecule.
Ig
Ig
X-linked Agammaglobulinemia
heavy chains
Heavy chains
The largest of polypeptide chains comprising immunoglobulins. They contain 450 to 600 amino acid residues per chain, and have molecular weights of 51-72 kda.
Immunoglobulins: Types and Functions start with rearrangement of diversity and joining segments to form the
pro-B cell
Pro-B cell
Lymphocytes: Histology. In the next step (pre-B cell),
Ig
Ig
X-linked Agammaglobulinemia heavy-chain
recombination
Recombination
Production of new arrangements of DNA by various mechanisms such as assortment and segregation, crossing over; gene conversion; genetic transformation; genetic conjugation; genetic transduction; or mixed infection of viruses.
Virology (
variable
Variable
Variables represent information about something that can change. The design of the measurement scales, or of the methods for obtaining information, will determine the data gathered and the characteristics of that data. As a result, a variable can be qualitative or quantitative, and may be further classified into subgroups.
Types of Variables, diversity, joining) is completed and the pre-B-cell
receptor
Receptor
Receptors are proteins located either on the surface of or within a cell that can bind to signaling molecules known as ligands (e.g., hormones) and cause some type of response within the cell.
Receptors is formed. Light-chain (kappa (κ) or lambda (λ)) rearrangement occurs, resulting in the expression of a complete
IgM
IgM
A class of immunoglobulin bearing mu chains (immunoglobulin mu-chains). Igm can fix complement. The name comes from its high molecular weight and originally being called a macroglobulin.
Immunoglobulins: Types and Functions-antibody molecule by an
immature B cell
Immature B cell
Lymphocytes: Histology. Formation of the
mature B cell
Mature B cell
Lymphocytes: Histology (naive) with both
IgM
IgM
A class of immunoglobulin bearing mu chains (immunoglobulin mu-chains). Igm can fix complement. The name comes from its high molecular weight and originally being called a macroglobulin.
Immunoglobulins: Types and Functions and
IgD
IgD
An immunoglobulin which accounts for less than 1% of plasma immunoglobulin. It is found on the membrane of many circulating B lymphocytes.
Immunoglobulins: Types and Functions follows.
Antigen
Antigen
Substances that are recognized by the immune system and induce an immune reaction.
Vaccination-dependent stages take place in secondary lymphoid tissues. Once the
mature B cell
Mature B cell
Lymphocytes: Histology produce
IgM
IgM
A class of immunoglobulin bearing mu chains (immunoglobulin mu-chains). Igm can fix complement. The name comes from its high molecular weight and originally being called a macroglobulin.
Immunoglobulins: Types and Functions and
IgD
IgD
An immunoglobulin which accounts for less than 1% of plasma immunoglobulin. It is found on the membrane of many circulating B lymphocytes.
Immunoglobulins: Types and Functions, a class switch can take place to make
IgE
IgE
An immunoglobulin associated with mast cells. Overexpression has been associated with allergic hypersensitivity.
Immunoglobulins: Types and Functions,
IgG
IgG
The major immunoglobulin isotype class in normal human serum. There are several isotype subclasses of igg, for example, igg1, igg2a, and igg2b.
Hypersensitivity Pneumonitis, and
IgA
IgA
Represents 15-20% of the human serum immunoglobulins, mostly as the 4-chain polymer in humans or dimer in other mammals. Secretory iga is the main immunoglobulin in secretions.
Immunoglobulins: Types and Functions. B cells are activated and become
plasma
Plasma
The residual portion of blood that is left after removal of blood cells by centrifugation without prior blood coagulation.
Transfusion Products cells or
memory cells
Memory cells
Cells that outlived a previous infection
Adaptive Immune Response.
The B cell migrates from the bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types marrow to the secondary lymphoid organs Lymphoid organs A system of organs and tissues that process and transport immune cells and lymph. Primary Lymphatic Organs. This process takes a number of measures to produce a functional differentiated B cell: activation by an antigen Antigen Substances that are recognized by the immune system and induce an immune reaction. Vaccination, proliferation, affinity maturation Affinity maturation Humoral Adaptive Immunity, class switching, and differentiation (into plasma Plasma The residual portion of blood that is left after removal of blood cells by centrifugation without prior blood coagulation. Transfusion Products or memory Memory Complex mental function having four distinct phases: (1) memorizing or learning, (2) retention, (3) recall, and (4) recognition. Clinically, it is usually subdivided into immediate, recent, and remote memory. Psychiatric Assessment cell).
Histologic section of the lymph Lymph The interstitial fluid that is in the lymphatic system. Secondary Lymphatic Organs node showing the cortex, paracortex Paracortex Secondary Lymphatic Organs and the medulla
Image by Geoffrey Meyer, edited by Lecturio.Structure and functional regions of a
lymph
Lymph
The interstitial fluid that is in the lymphatic system.
Secondary Lymphatic Organs node: comprise a
collagen
Collagen
A polypeptide substance comprising about one third of the total protein in mammalian organisms. It is the main constituent of skin; connective tissue; and the organic substance of bones (bone and bones) and teeth (tooth).
Connective Tissue: Histology-rich
fibrous
Fibrous
Fibrocystic Change
capsule
Capsule
An envelope of loose gel surrounding a bacterial cell which is associated with the virulence of pathogenic bacteria. Some capsules have a well-defined border, whereas others form a slime layer that trails off into the medium. Most capsules consist of relatively simple polysaccharides but there are some bacteria whose capsules are made of polypeptides.
Bacteroides and an underlying
subcapsular sinus
Subcapsular sinus
Secondary Lymphatic Organs (SCS).
Cells are segregated into (1) the cortex (consisting of B cells, T
follicular helper cells
Follicular helper cells
A specialized subpopulation of CD4+ T cells involved in formation of germinal center. Tfh cells are mostly located in secondary lymphoid organs, e.g., tonsil; spleen and lymph nodes. They are CD4 antigen; CD45 antigen; b-cell lymphoma 6 protein; cxcr5 receptors; icos inducible t-cell co-stimulator; and pd1 receptor positive.
T cells: Types and Functions, and
follicular dendritic cells
Follicular dendritic cells
Non-hematopoietic cells, with extensive dendritic processes, found in the primary and secondary follicles of lymphoid tissue (the B cell zones). They are different from conventional dendritic cells associated with T-cells. They are derived from mesenchymal stem cells and are negative for class II mhc antigen and do not process or present antigen like the conventional dendritic cells do. Instead, follicular dendritic cells have fc receptors and C3b receptors that hold antigen in the form of antigen-antibody complexes on their surfaces for long periods for recognition by B-cells.
MALT Lymphoma [FDCs] arranged in
primary follicles
Primary follicles
Secondary Lymphatic Organs, in which B cells survey antigens presented on the FDC stromal network); and (2) the
paracortex
Paracortex
Secondary Lymphatic Organs (accommodates
T cells
T cells
Lymphocytes responsible for cell-mediated immunity. Two types have been identified – cytotoxic (t-lymphocytes, cytotoxic) and helper T-lymphocytes (t-lymphocytes, helper-inducer). They are formed when lymphocytes circulate through the thymus gland and differentiate to thymocytes. When exposed to an antigen, they divide rapidly and produce large numbers of new T cells sensitized to that antigen.
T cells: Types and Functions,
dendritic cells
Dendritic cells
Specialized cells of the hematopoietic system that have branch-like extensions. They are found throughout the lymphatic system, and in non-lymphoid tissues such as skin and the epithelia of the intestinal, respiratory, and reproductive tracts. They trap and process antigens, and present them to T-cells, thereby stimulating cell-mediated immunity. They are different from the non-hematopoietic follicular dendritic cells, which have a similar morphology and immune system function, but with respect to humoral immunity (antibody production).
Skin: Structure and Functions [DCs], and fibroblastic reticular cells [FRCs] which form stromal cell networks and reticular fibers).
The inner medulla is composed of lymphatic tissues (medullary cords) separated by medullary sinuses consisting of
lymph
Lymph
The interstitial fluid that is in the lymphatic system.
Secondary Lymphatic Organs.
B-cell activation by antigen Antigen Substances that are recognized by the immune system and induce an immune reaction. Vaccination presentation Presentation The position or orientation of the fetus at near term or during obstetric labor, determined by its relation to the spine of the mother and the birth canal. The normal position is a vertical, cephalic presentation with the fetal vertex flexed on the neck. Normal and Abnormal Labor can have different paths:
B-cell activation (T-cell-dependent):
Circulating
antigen
Antigen
Substances that are recognized by the immune system and induce an immune reaction.
Vaccination interacts with the
BCR
BCR
Lymphocytes: Histology of the B cell. The
antigen
Antigen
Substances that are recognized by the immune system and induce an immune reaction.
Vaccination is endocytosed and degraded and the peptide components are complexed with cell surface MHC II molecules. T follicular helper (Tfh) cells (specialized CD4+ T helper cells) recognize and
bind
BIND
Hyperbilirubinemia of the Newborn the
antigen
Antigen
Substances that are recognized by the immune system and induce an immune reaction.
Vaccination–MHC II complex.
Cytokines
Cytokines
Non-antibody proteins secreted by inflammatory leukocytes and some non-leukocytic cells, that act as intercellular mediators. They differ from classical hormones in that they are produced by a number of tissue or cell types rather than by specialized glands. They generally act locally in a paracrine or autocrine rather than endocrine manner.
Adaptive Immune Response are released by the Tfh cells, leading to B-cell activation and proliferation.
Activated B cells
Activated B cells
Humoral Adaptive Immunity enter the germinal centers, where they continue the process, leading to differentiation.
B-cell activation and maturation processes taking place in the germinal center:
On activation, the B cell moves from the mantle zone and enters the germinal center. B-cell proliferation (
clonal expansion
Clonal Expansion
Seborrheic Keratosis) takes place and antibody affinity to the
antigen
Antigen
Substances that are recognized by the immune system and induce an immune reaction.
Vaccination is enhanced through the process of somatic hypermutation. Repeated cycles of proliferation and hypermutation fine-tune the B-cell
receptor
Receptor
Receptors are proteins located either on the surface of or within a cell that can bind to signaling molecules known as ligands (e.g., hormones) and cause some type of response within the cell.
Receptors. However, not all B cells continue to differentiate, especially if the affinity is weak.
Apoptosis
Apoptosis
A regulated cell death mechanism characterized by distinctive morphologic changes in the nucleus and cytoplasm, including the endonucleolytic cleavage of genomic DNA, at regularly spaced, internucleosomal sites, I.e., DNA fragmentation. It is genetically-programmed and serves as a balance to mitosis in regulating the size of animal tissues and in mediating pathologic processes associated with tumor growth.
Ischemic Cell Damage follows if the
antigen
Antigen
Substances that are recognized by the immune system and induce an immune reaction.
Vaccination–antibody binding is not optimized. Those with strong affinity survive (selection), with the help of survival signals from
follicular dendritic cells
Follicular dendritic cells
Non-hematopoietic cells, with extensive dendritic processes, found in the primary and secondary follicles of lymphoid tissue (the B cell zones). They are different from conventional dendritic cells associated with T-cells. They are derived from mesenchymal stem cells and are negative for class II mhc antigen and do not process or present antigen like the conventional dendritic cells do. Instead, follicular dendritic cells have fc receptors and C3b receptors that hold antigen in the form of antigen-antibody complexes on their surfaces for long periods for recognition by B-cells.
MALT Lymphoma (DC) and
T cells
T cells
Lymphocytes responsible for cell-mediated immunity. Two types have been identified – cytotoxic (t-lymphocytes, cytotoxic) and helper T-lymphocytes (t-lymphocytes, helper-inducer). They are formed when lymphocytes circulate through the thymus gland and differentiate to thymocytes. When exposed to an antigen, they divide rapidly and produce large numbers of new T cells sensitized to that antigen.
T cells: Types and Functions. These selected B cells move on to class switching and differentiation into
plasma
Plasma
The residual portion of blood that is left after removal of blood cells by centrifugation without prior blood coagulation.
Transfusion Products cells or
memory cells
Memory cells
Cells that outlived a previous infection
Adaptive Immune Response.
Germinal center: histology of the germinal center of a secondary lymphoid tissue
LZ: light zone
DZ: dark zone
Summary of B cell development to differentiation (from
bone
Bone
Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy.
Bones: Structure and Types marrow to secondary lymphoid organ):
B cell development:
In the
bone
Bone
Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy.
Bones: Structure and Types marrow, B cells develop into immature B cells, a process in which the B-cell
receptor
Receptor
Receptors are proteins located either on the surface of or within a cell that can bind to signaling molecules known as ligands (e.g., hormones) and cause some type of response within the cell.
Receptors (
BCR
BCR
Lymphocytes: Histology) is assembled. Then the B cell migrates to the secondary
lymphoid organs
Lymphoid organs
A system of organs and tissues that process and transport immune cells and lymph.
Primary Lymphatic Organs, where activation occurs.
B cell activation
B cell activation
Humoral Adaptive Immunity:
The
antigen
Antigen
Substances that are recognized by the immune system and induce an immune reaction.
Vaccination binds the B cell with the “best match”
BCR
BCR
Lymphocytes: Histology. One pathway of activation is T-cell–independent, whereby the
activated B cell
Activated B cell
Lymphocytes: Histology is triggered to differentiate into a short-lived
plasma cell
Plasma cell
Specialized forms of antibody-producing B-lymphocytes. They synthesize and secrete immunoglobulin. They are found only in lymphoid organs and at sites of immune responses and normally do not circulate in the blood or lymph.
Lymphocytes: Histology (producing
antibodies
Antibodies
Immunoglobulins (Igs), also known as antibodies, are glycoprotein molecules produced by plasma cells that act in immune responses by recognizing and binding particular antigens. The various Ig classes are IgG (the most abundant), IgM, IgE, IgD, and IgA, which differ in their biologic features, structure, target specificity, and distribution.
Immunoglobulins: Types and Functions) without the help of the T cell. In T-cell–dependent activation, the T cell recognizes the
antigen
Antigen
Substances that are recognized by the immune system and induce an immune reaction.
Vaccination–MHC II and
triggers
Triggers
Hereditary Angioedema (C1 Esterase Inhibitor Deficiency) proliferation of the B cell in the germinal center of the lymphoid tissue.
Proliferation and maturation:
The process is followed by somatic hypermutation (SHM; a programmed
mutation
Mutation
Genetic mutations are errors in DNA that can cause protein misfolding and dysfunction. There are various types of mutations, including chromosomal, point, frameshift, and expansion mutations.
Types of Mutations to further fine-tune the affinity of the antibody to the
antigen
Antigen
Substances that are recognized by the immune system and induce an immune reaction.
Vaccination). Repeated cycles of proliferation and hypermutation refine the
BCR
BCR
Lymphocytes: Histology. Only those with the best affinity will be selected and survive; those with low affinity will undergo
apoptosis
Apoptosis
A regulated cell death mechanism characterized by distinctive morphologic changes in the nucleus and cytoplasm, including the endonucleolytic cleavage of genomic DNA, at regularly spaced, internucleosomal sites, I.e., DNA fragmentation. It is genetically-programmed and serves as a balance to mitosis in regulating the size of animal tissues and in mediating pathologic processes associated with tumor growth.
Ischemic Cell Damage. The surviving B cells then go through class-switch
recombination
Recombination
Production of new arrangements of DNA by various mechanisms such as assortment and segregation, crossing over; gene conversion; genetic transformation; genetic conjugation; genetic transduction; or mixed infection of viruses.
Virology (CSR), in which the heavy chain makeup is changed (
IgM
IgM
A class of immunoglobulin bearing mu chains (immunoglobulin mu-chains). Igm can fix complement. The name comes from its high molecular weight and originally being called a macroglobulin.
Immunoglobulins: Types and Functions to other isotypes) with the help of
cytokines
Cytokines
Non-antibody proteins secreted by inflammatory leukocytes and some non-leukocytic cells, that act as intercellular mediators. They differ from classical hormones in that they are produced by a number of tissue or cell types rather than by specialized glands. They generally act locally in a paracrine or autocrine rather than endocrine manner.
Adaptive Immune Response.
Differentiation:
These B cells then differentiate into
plasma
Plasma
The residual portion of blood that is left after removal of blood cells by centrifugation without prior blood coagulation.
Transfusion Products cells and
memory cells
Memory cells
Cells that outlived a previous infection
Adaptive Immune Response, leaving the germinal center.
From the initial B-cell production, many processes allow humans to produce different antibody molecules that are significantly more than the number of genes Genes A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. DNA Types and Structure in the genome Genome The complete genetic complement contained in the DNA of a set of chromosomes in a human. The length of the human genome is about 3 billion base pairs. Basic Terms of Genetics.
It is estimated that billions of antibodies Antibodies Immunoglobulins (Igs), also known as antibodies, are glycoprotein molecules produced by plasma cells that act in immune responses by recognizing and binding particular antigens. The various Ig classes are IgG (the most abundant), IgM, IgE, IgD, and IgA, which differ in their biologic features, structure, target specificity, and distribution. Immunoglobulins: Types and Functions are generated, compared to about 30,000 genes Genes A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. DNA Types and Structure.
The immune system Immune system The body’s defense mechanism against foreign organisms or substances and deviant native cells. It includes the humoral immune response and the cell-mediated response and consists of a complex of interrelated cellular, molecular, and genetic components. Primary Lymphatic Organs has unique mechanisms to create antibody diversity, which include: