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B-Cell Immunodeficiencies: Common Variable Immunodeficiency, X-linked Agammaglobulinemia and Selective IgA Deficiency – Primary Immunodeficiency
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Slides Immunodeficiency.pdf
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00:01 Examples of primary immunodeficiencies affecting B-cells include common variable immunodeficiency, X-linked agammaglobulinemia, selective IgA deficiency. 00:21 So looking first at common variable immunodeficiency; in patients with this condition, there is low IgG, and IgA and/or IgM. 00:42 The gene defects in most patients have yet to be fully defined. 00:49 But in some patients, mutations have been identified in a number of different molecules important in the B-cell response - TAC1, CD19, ICOS, substance P, MHC Class II, various complement components, mismatch repair protein MSH5, B-cell surface receptor BAFF. And these patients have recurrent infections with a number of different species - S. pneumoniae, Hemophilus influenza, Mycoplasma species and so forth. 01:32 In X-linked agammaglobulinemia, as the name suggests, the gene is on the X chromosome. 01:38 And agammaglobulinemia means without gamma globulins. 01:43 And most of the gamma globulins are the immunoglobulins. 01:47 This is due to mutations in the Bruton’s tyrosine kinase or Btk gene. 01:53 There’s a developmental defect at the pre-B stage. 01:59 Antibody production is grossly compromised. 02:03 And there are infections with a number of different pyogenic bacteria, and also with the fungus pneumocystis jirovecii. Looking at selective IgA deficiency, both circulating IgA and secretory dimeric IgA are affected. 02:20 The gene defects in most patients have yet to be discovered. 02:25 Maybe you’ve got selective IgA deficiency and you don’t even know about it, you’ll be absolutely fine. 02:30 Most patients, there’s no consequence. 02:33 And this is because other classes of antibody, including IgM transported to mucosal surfaces by the poly-Ig receptor compensate for the lack of IgA. 02:45 It’s actually quite a common theme in immunology, that there are lots of different mechanisms that can take over if one is defective.
About the Lecture
The lecture B-Cell Immunodeficiencies: Common Variable Immunodeficiency, X-linked Agammaglobulinemia and Selective IgA Deficiency – Primary Immunodeficiency by Peter Delves, PhD is from the course Immunodeficiency and Immune Deficiency Diseases. It contains the following chapters:
- Examples of Primary Immunodeficiency Affecting B-cells
- Common Variable Immunodeficiency
- X-Linked Agammaglobulinemia
- Selective IgA Deficiency
Included Quiz Questions
X-linked agammaglobulinemia is caused by a mutation in which of the following genes?
- Bruton’s tyrosine kinase
- gp91phox
- MEFV
- TNFRSF13C
- Inducible T-cell COStimulator (ICOS)
Which of the following is NOT true regarding selective IgA deficiency?
- Most patients are severely immunocompromised.
- Circulating IgA and secretory dimeric IgA are affected.
- A causative gene defect has not been identified.
- Other immune mechanisms may often compensate.
- Normal antibody response to vaccinations occurs.
Author of lecture B-Cell Immunodeficiencies: Common Variable Immunodeficiency, X-linked Agammaglobulinemia and Selective IgA Deficiency – Primary Immunodeficiency
Peter Delves, PhD
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The lecture was amazing, it had all the important details that my textbook had, but at the same time it was very punctual and didactic. I was able to visualize all the things that I read with good examples.
