White cell disorders: investigation of neutropenia, leukaemia and leukaemoid reactions

Question 1

Types of WBC

Answer 1

Granulocytes:

• neutrophils
• basophils
• eosinophils

Lymphocytes:

• B cells
• T cells

-monocytes (and macrophages)

Question 2

function of neutrophils

Answer 2

chemotaxis, phagocytosis, killing of phagocytosed bacteria

Question 3

function of basophils

Answer 3

Mediate immediate type hypersensitivity (IgE), modulate inflammatory responses by releasing heparin and proteases

Question 4

function of eosinophils

Answer 4

All neutrophil functions (chemotaxis, phagocytosis, killing of phagocytosed bacteria) as well as antibody dependent damage to paracites, regulate immediate type hypersensitivity reactions (inactivating histamine and leukotrienes released by basophils and mast cells)

Question 5

function of B cells

Answer 5

B Cells: 10-30%: effectors of humoral immunity –i.e. Antibody production
40% IgM , 30% IgD, 30% IgG and 10% IgA
kappa light chain or lamda light chain (normal ratio 2:1)
Activated B cells develop into plasma cells

Question 6

function of T cells

Answer 6

grade intracellular pathogens such as mycobacteria.
Interaction with B cells in producing antibodies against certain antigens
Participation in delayed hypersensitivity reactions

Question 7

function of monocytes and macrophages

Answer 7

Chemotaxis, phagocytosis, killing of some micro organisms, antigen presentation and modulation of inflammatory response

Question 8

causes of neutrophilia

Answer 8

-bacterial infection
-inflammation
-drugs/medication- commonly caused by steroids (cause neutrophilia and lymphopenia),
-primary haematological malignancy e.g. acute leukaemia
-dietary e.g. B12, folate, copper
-pregnancy
-lactation
-exercise
-neonates
-burns
-rheumatoid arthritis
-vasculitis
0MI
-uraemia
-DKA
-smoking

Question 9

define leukaemia

Answer 9

blood cancer derived from the bone marrow

Question 10

causes of congenital neutropenia

Answer 10

• constitutional
• ethnic e.g Afro-Carribean and Chinese have lower normal neutrophil count compared to Caucasian popoluation
• severe congenital neutropenia
• cyclic neutropenia
• Fanconi anaemia
• Chediak-Higashi

Question 11

how to investigate a neutropenic patient

Answer 11

-Age
-History: Infections, drug exposure, autoimmunity
B symptoms/bleeding
-Family History
-Examination: Syndromic features, infection, skin, changes/arthropathy, hepatosplenomegaly, lymphadenopathy
-Investigations: FBC,
Blood film, Haematinics, viral screen, TFTs, autoimmune screen
Second line
Chest xray
USS abdomen
Bone marrow biopsy

Question 12

leukaemia investigations

Answer 12

FBC
U&Es/LFTS/CRP
Coagulation
Virology
Blood film
Bone marrow
morphology, immunophenotyping, Cytogenetics, molecular analysis

Question 13

define leukocytosis

Answer 13

increase in total white cell count

Question 14

describe white cell changes in inflammation

Answer 14

• Neutrophilia with toxic granulation and left shift secondary to accelerated neutrophil production
• Usually accompanied by raised PLT
• Leukaemoid reaction: WBC>50,000/microLfrom causes other than leukemia,; mature neutrophils; accompanied by increased numbers of bands, metamyelocytes,and/ormyelocytes

Question 15

causes of neutropenia

Answer 15

• drugs e.g. chemotherapy, antipsychotics- clozapine, antibiotics
• viral infections e.g. HIV, dengue fever
• splenomegaly
• autoimmune
• dietary e.g. B12 or folate deficiency
• BM infiltration