White Cell Disorders – Diseases of the Blood System

00:00 Let's just turn now to white cell disorders. Here perhaps there may be a deficiency of white cells.

00:08 That puts the patient at risk of infection because that is the major function of this class of blood cell.

00:17 Now low neutrophils goes under the term neutropenia. There are many causes for this.

00:22 Sometimes it's a drug reaction. Sometimes it might be an infection itself or of course it could be seen as part of a general bone marrow problem.

00:36 The normal neutrophil count is around 2x10^9 per litre. But infection becomes a serious risk when that count falls below 0.5 and indeed when we're giving chemotherapy to patients with cancer, we can often see it below 0.1 and here, the patient becomes at high risk of severe infection.

01:00 Example on the right you can see a patient with a very nasty infection of the skin.

01:06 Lymphocytes can also be reduced in the count. That's called LYMPHOPENIA. That's slightly less common, but you can see it from of course the immune deficiencies and there's a wide variety of those.

01:21 However, perhaps the biggest problem that we see with white cells is not when they are reduced, but when they are increased. And that of course is called LEUKAEMIA. Let me just introduce you to leukaemia.

01:36 The word interestingly comes from Greek, it means white blood. I am not up here to teach you classics and I certainly wouldn't be able to as I never learned any but that is an interesting phrase because it reminds us here that tumor cells are in the blood, too many white cells in the blood and the bone marrow.

01:57 Down the side of this graph here, we've got a range of different malignant diseases:leukaemias and indeed lymphomas And on the X-axis on the bottom here, you can see the age at which these arise, the median or average age at which these arise. I think there's two things to note: Firstly most of these diseases are occurring in older people perhaps near the age of 70.

02:26 Of course, that's common in most cancers. Cancers get more common as we age because we acquire more mutations in our DNA.

02:35 Secondly notice two disorders, which are seen in younger people.

02:40 Near the top there, you can see acute lymphoblastic leukaemia, the most common malignant disease in children and you can see the median age is much reduced. and in the middle layer, Hodgkin's lymphoma that's also often seen in younger people perhaps around the age of 20.

03:01 Those two disorders slightly stand out and we will discuss them in more detail in other lectures.

03:09 So here we are, leukaemia and I've mentioned already, this means white blood, an increase in the white cell count in the blood. And haematologists, like many doctors and scientists love to classify things into different groups. Leukaemia is no different.

03:29 There are four major types, two subdivisions. Acute leukaemia and chronic leukaemia.

03:37 What do those terms mean? An ACUTE leukaemia develops quite rapidly.

03:42 It is an aggressive disease. It can be fatal within weeks unless it is treated.

03:47 Whereas CHRONIC disease is slower growing. It takes more time to develop.

03:53 It is less of a threat to the patient in the short term. Now both acute and chronic leukaemia can be further subdivided into lymphoid or myeloid and this refers to the lineage of cells to which the leukaemia belongs to.

04:12 A lymphoid leukaemia would be derived from B-cells or T-cells, whereas myeloid leukaemia derives from many of those cells down the myeloid lineage - neutrophils, erythroblasts, megakaryocytes and platelets.

04:29 Now we need to classify leukaemia into these four types because the treatments are very specific for each type, and these are improving every year. We are now getting very good results from the treatment of leukaemia but there's more that we need to do.

04:45 Lymphoma. There's often confusion between the difference between leukaemia and lymphoma, but it's really quite straightforward. Lymphoma is a disease in which the malignant white cells accumulate within the lymphoid tissue rather than within the blood.

05:05 You'll see on the right there the diagram showing some of the lymph node groups that we all have within our neck.

05:14 We have many lymph node groups around the body, 95% of our lymphocytes live within lymphoid tissue.

05:23 Now within lymphoma, the point you need to remember is that there are two main subtypes: Hodgkin lymphoma and non-Hodgkin lymphoma. Non-Hodgkin lymphoma includes many many different subtypes of lymphoma and the cell that distinguishes these two types is called the Reed-Sternberg cell.

05:45 I will explain that in much more detail in the lecture on lymphomas.