Introduction to haematology Flashcards
Haemopoiesis
physiological development process that gives rise to the cellular components of blood
Symmetric self-renewal
Resting stem cell; rely on them in the times of stress e.g. in injury
Asymmetric self-renewal
giving rise to a differentiated cell and a stem cell – maintains stem cell pool
What are the 2 blood lineages
- myeloid and lymphoid
Erythrocytes
- 120 day lifespan
- haemoglobin for oxygen
- Low red cells = anaemia
- High RC = polycythaemia
Relative polycythaemia
plasma volume is reduced but cell number stays same. RBC are suspended in plasma = increased proportion
Leukocytes (WBCs)
- Immunity and host defence
- Granulocytes - have cytoplasmic granules
Neutrophils
- Phagocytes
- Most common white cell -fairly short lived
- Lobed nucleus - can be reduced in myelodysplasia and in other malignant diseases. Lobes can increase = hypersegmented – seen in b12 anaemia or folic acid deficient
- Increased numbers = neutrophilia = seen in infection; particularly bacterial. Decreased numbers = neutropenia = seen in response to chemo/side effect of drugs
- Eosinophils
- Nucleus is bilobed and granules are orange/red
- Fights parasitic infections and allergies
- Increased numbers = eosinophilia - occurs during use of aspirin
- Basophils
- Rare cells – dark heavily granulated cells
- Found in CML (chronic myeloid leukaemia)
- Increased numbers = basophilia
Monocytes
- Phagocytic and antigen presenting cells
- Can migrate to tissues and are then identified as macrophages or histiocytes
- Increased numbers = monocytosis caused by diseases like TB
Platelets
- Derived from bone marrow megakaryocytes (have many nuclei)
- form part of the blood clotting system, Aggregate to plug holes in damaged blood vessels
Lymphocytes
- Increased numbers = lymphocytosis – e.g. atypical in glandular fever, CLL (accumulation of mature looking lymphocytes)
- Decreased numbers = lymphopenia – e.g. in bone marrow transplant and infection
Natural killer cells
- Innate immune system – don’t rely on human leukocyte antigen system
- Larger granular lymphocytes
- Recognise “non-self”
T lymphocytes
- Adaptive immune system – dependent on HLA system
- Multiple sub-types
- Involved in cell-mediated immunity
- Interact with B cells and macrophages- Regulate immune responses
B lymphocytes
- Adaptive immune system
- Rearrange IG genes to enable antigen specific antibody production
- Humoral immunity – make antibodies
- Increase numbers of plasma cells = plasmacytosis
Full Blood Count
- taken in EDTA anticoagulated blood bottle
Measures: - Haemoglobin concentration
- Red cell parameters (MCV = mean cell volume and MCH = mean cell haemoglobin content)
- White cell count (WCC)
- Platelet count
When interpreting FBC be alert of:
- Technical problems e.g. thrombocytopenia
- Abnormal results
- Serious urgent abnormalities
Blood film
- blood on film, get a tail of blood cells that separate to look down microscope
Coagulation screen
- Measures time taken for a clot to form when plasma is mixed with specific reagents
- PT = prothrombin time
- APTT = activated partial thromboplastin time
- TT = thrombin time
Bone Marrow Aspirate and Trephine
- Aspirate = liquid marrow aspirated from posterior iliac crest – looks at the cells in them
- Trephine = core biopsy is taken to look at bone marrow architecture
Anaemias
- Defined as Hb below 130 (male) or 115 (female)
Microcytic hypochromic anaemia
- Microcytic = small red cells - MCV < 80
- Hypochromic = low Hb per cell – MCH < 27 – cells look paler than usual
- Causes = iron deficiency, thalassaemia, chronic disease
Normocytic normochromic anaemia
- Normal cell size and normal Hb per cell – MCV = 80-95, MCH > 27
- Causes = haemolytic anaemia, chronic disease, acute blood loss, bone marrow failure
Macrocytic anaemia
- MCV > 95 but normal Hb per cell = MCH > 27
2 types: - Megaloblastic = inadequate development of nucleus – causes = vitamin B12 deficiency or folate deficiency
- Non-megaloblastic = big cells but no nuclear dysmorphia - causes = alcohol, myelodysplasia
Sickle cell =
associated with haemolysis and thrombosis
