Laboratory Investigation of White Cell Disorders Flashcards
Describe the role of lymphocytes and the 3 main types.
- Adaptive immune response - differentiation between self and non-self, produce antibodies.
- Memory cells.
- 3 cell types: T cells, B cells, natural killer (NK) cells.
- T cells - cell-mediated immunity - CD4+ T-helper cells, CD8+ cytotoxic T-cells.
- B-cells - humoral immunity - antibody production.
- NK cells - innate immune system - attack virally infected cells and tumour cells.
Name the derivatives of the myeloid and lymphoid progenitor cells.
Myeloid progenitor:
- Neutrophils
- Monocytes
- Eosinophils
- Basophils
- Erythroid > red blood cell
- Megakaryocytes > platelets
Lymphoid progenitor:
- B cells
- T cells
- NK cells
Describe the normal range for WBC and neutrophil count and the disorders arising from aberrant numbers.
- WBC normal range = 4.0 - 11.0 x 109 / L
- Neutrophil normal range = 2.0 - 7.5 x 109 / L
- Leucocytosis - increase in WBC
- Leucopenia - decrease in WBC
- Neutrophilia - increase in neutrophils
- Neutropenia - decrease in neutrophils
Name the physiological and pathological causes of neutrophilia.
Normal physiological reaction: Post-operative, pregnancy
Other causes:
- Bacterial infection
- Inflammation - e.g. vasculitis
- Carcinoma
- Steroid treatment
- Myeloproliferative disorders
- Treatment with myeloid growth factors
Describe the changes that may be associated with neutrophilia.
- Toxic granulation - seen in severe infection
- Shift to the left - increased proportion of premature neutrophils and precursors (myeloid progenitors) in the blood.
- Shift to the right - increased proportion of hypersegmented neutrophils.
- Dohle bodies - blue inclusions on periphery of neutrophils - often seen with toxic granulation.
What investigations should be undertaken if neutrophilia is found?
- FBC, differential WBC count
- Blood film examination
- Bacterial culture screen for infection
- Bone marrow examination
- Chromosome analysis for chronic myeloid leukaemia - Philadelphia chromosome (translocation between 9 and 22), molecular analysis for BCR-ABL oncogene
Name the causes of neutropenia.
- Viral infection
- Drug-induced - e.g. sulphonamides
- Radiotherapy and chemotherapy
- Part of pancytopenia in bone marrow failure (aplastic anaemia) or infiltration e.g. leukaemia
- Racial - “benign ethnic neutropenia”
Describe the possible causes and investigation of eosinophilia.
- Causes - allergic diseases, parasitic infections, drug sensitivity, myeloproliferative diseases e.g. chronic myeloid leukaemia, Hodgkin’s lymphoma.
- Investigation - FBC, differential WBC count, blood film examination, stool examination for ova and parasites.
Describe the possible causes and investigation of monocytosis.
- Causes - tuberculosis, leukaemia, malaria.
- Investigation - FBC, differential WBC count, blood film examination for abnormal WBCs + malarial parasites, bone marrow examination for leukaemia, TB cultures.
Describe the possible causes and investigation of lymphocytosis.
Causes:
- Lymphocytosis of childhood (1-6 years) - normal
- Bacterial or viral infection
- Leukaemias and lymphomas
Investigation:
- FBC and differential WBC count
- Blood film examination - atypical mononuclear cells - glandular fever (caused by EBV)?
- Infectious mononucleosis (glandular fever) test
Outline the cause of infectious mononucleosis.
- Usually caused by Epstein-Barr Virus (EBV).
- Acute infection results in production of heterophile antibodies - antibodies which react against a different antigen to the one that stimulated the reaction.
- Presence of heterophile antibodies confirms diagnosis.
How is lymphocytosis with mature lymphocytes investigated?
- Chronic lymphocytic leukaemia or lymphoma?
- Immunophenotyping.
- Do B-cells demonstrate clonality by light-chain restriction?
- Do T-cells demonstrate clonality by T-cell receptor gene rearrangement studies?
