Abnormal White Blood Cell Count Flashcards
What is the lymphoid lineage?
Lymphoid cells are lymphocytes = T cells, B cells and NK cells
Which cells come under the myeloid lineage?
Erythrocytes Neutrophils Basophils Eosinophils Monocytes Macrophages Megakaryocytes Dendritic Cells
Describe how the appearance of white cells changes as they develop.
They become smaller and their cytoplasm becomes clearer.
Which factors stimulate the following cell lines:
a. Lymphoid
b. Myeloid
c. Erythroid
a. Lymphoid - IL-2
b. Myeloid - G-CSF, M-CSF
c. Erythroid - Erythropoietin
Define Leukaemia.
A malignant progressive disease in which the bone marrow and other blood-forming organs produce increased numbers of immature or abnormal leukocytes.
This leads to suppression of the production of other blood cells such as erythrocytes, granulocytes and platelets.
Define Lymphoma.
A group of blood cell tumours that develop from lymphatic cells.
If the disease is mainly in the lymphatic tissue then it is lymphoma.
If it is mainly in the blood it is leukaemia.
Define Myeloma.
A malignant disease of the bone marrow characterised by two or moreof the following criteria:
The presence of an excess of abnormal plasma cells in the bone marrow
Typical lytic deposits in the bones on X-ray, giving the appearance of holes
The presence in the serum of abnormal gammaglobulin, usually IgG
Broadly speaking, what can cause an increase in white blood cell count?
Increased white blood cell production
Increased white blood cell survival
What two broad categories of diseases can cause an increase in white blood cell count?
Reactive – in response to infection or inflammation
Primary – malignant
What is the difference in the type of white blood cell seen in theperipheral blood of someone with an infection/inflammation (reactive) and someone with a malignancy (primary)?
Reactive – only mature white blood cells
Primary – mature AND immature white blood cells present
Where does the mutation occur in chronic myeloid leukaemia?
GM-CFC phase (granulocyte-monocyte colony forming cell)
If there are only immature cells in the blood film with low haemoglobin and low platelets, what would you suspect?
Acute leukaemia
What are the normal ranges of:
a. Hb
b. Platelets
c. WCC
d. Neutrophils
e. Lymphocytes
f. Monocytes
g. Eosinophils
h. Basophils
a.Hb 120-160 g/L b. Platelets 150-400 x 109/L c.WCC 4-11 x 109/L d. Neutrophils 2.5-7.5 x 109/L e. Lymphocytes 1.5-3.5 x 109/L f. Monocytes 0.2-0.8 x 109/L g. Eosinophils 0.04-0.44 x 109/L h. Basophils 0.01-0.1 x 109/L
What can cause an elevated lymphocyte count?
Viral infections
Chronic lymphocytic leukaemia
What is the lifespan of a neutrophil?
Hours in the peripheral blood
2-3 days in the tissues
What is margination of neutrophils?
Around 50% of neutrophils in the circulation have marginated meaning that they have stuck to the wall of a damaged vessel (this means that they are NOT counted in the full blood count)
Describe the differences in the appearance of neutrophils in infection compared to leukaemia.
Neutrophils in infection are granular (show toxic granulation)
Neutrophils in leukaemia do not have granules and do not look toxic.
What else would be present in the blood film of someone with leukaemia that would not be present in someone with an infection?
Myelocytes and metamyelocytes – these precursors would not be found in the peripheral blood of someone responding to infection
State some causes of neutrophilia.
Infection Inflammation Physical stress Adrenaline Corticosteroids Underlying neoplasia Malignant neutrophilia (myeloproliferative disorders, chronic myeloid leukaemia)
What types of infection cause neutrophilia?
Bacterial
Fungal
Certain viral infections Generally: if the neutrophil count is low but there are other features of infection, then you can deduce that it’s a viral infection
State some infections that characteristically do NOT produce neutrophilia.
Brucella
Typhoid
Many viral infections
State some reactive causes of eosinophilia.
Parasitic infection
Allergic diseases e.g. asthma Neoplasms e.g. Hodgkin’s and Non-Hodgkin’s Hypereosinophilic syndrome
State a malignant cause of eosinophilia.
Malignant chronic eosinophilic leukaemia (INCREDIBLY RARE)
What would you see in the chest X-ray of someone with Hodgkin’s lymphoma?
Increased mediastinal mass
What can cause monocytosis?
RARE but it is seen in certain chronic infections and primary haematological disorders
TB, brucella, typhoid
CMV, varicella zoster
Sarcoidosis
Chronic myelomonocytic leukaemia (MDS – myelodysplastic syndrome)
Describe the appearance of chronic lymphocytic leukaemia on a blood film.
The lymphocytes have a typical appearance – big nucleus + little cytoplasm
They are mature lymphocytes
This appearance can also be present in autoimmune and inflammatory conditions
Describe the appearance of acute lymphoblastic leukaemia on a blood film.
There are immature lymphoblasts
They are much larger than the mature lymphocytes
Within the large nucleus you can see the nucleolus (showing that the cell is immature)
Describe the difference in the expansion of lymphocytes in secondary (reactive) lymphocytosis compared to primary lymphocytosis.
Secondary lymphocytosis = polyclonal expansion
Primary lymphocytosis = monoclonal expansion
State some causes of reactive lymphocytosis.
Infection (e.g. EBV, toxoplasma, infectious hepatitis, rubella, herpes infections)
Autoimmune disorders
Neoplasia
Sarcoidosis
What do you see in the blood film of someone with mononucleosis syndrome?
Atypical lymphocytes
They look similar to immature lymphocytes but they aren’t very round an its cytoplasm extends between surrounding cells
The nucleus of the cell lacks nucleoli
This is typical of glandular fever
So if there is a high WCC and you find these reactive-looking lymphocytes you can suspect that it is a reactive, infection-induced lymphocytosis
What is glandular fever caused by?
Epstein-Barr virus infection of the B-lymphocytes via the CD21 receptor
Infected B-cells proliferate and express EBV associated antigen
There is a cytotoxic T-lymphocyte response
Acute infection is resolved leading to life-long sub-clinical infection
What is the usual cause of lymphocytosis in elderly people?
Chronic lymphocytic leukaemia (CLL)
Explain how light chain restriction can be used to distinguish between causes of lymphocytosis.
In reactive lymphocytosis, there will be polyclonal expansion of the lymphocytes meaning that the light chains of the antigens produced by B cells and the B cell receptors will have a 50:50 kappa and lambda divide
In primary lymphocytosis, there will be a monoclonal expansion so you will get kappa or lambda restriction meaning that all the light chains are of one type
Normally, B and T cells will undergo gene rearrangement in the TCR and Ig genes in a process called affinity maturation. How is this different in primary monoclonal proliferation of B and T cells?
With primary monoclonal proliferation, all the daughter cells carry identical copies of Ig genes or TCR genes
