Haematology - WBCs and platelets Flashcards
What are the functions of each WBC?
Neutrophil and monocyte - phagocytosis (innate immunity)
Lymphocyte - able to recognise antigens (T and B cells, adaptive immunity)
Eosinophils and basophils - defines against parasites and allergies
Which cells are polymorphonuclear/granulocytes?
Neutrophil - granules not visible with stains
Eosinophil
Basophil
All the phils
Which are the largest and smallest WBCs?
Largest - monocyte
Smallest - lymphocyte
What are immature neutrophils called?
Band cells
How many WBCs are seen in a 10X field to presume leucocytosis or leucocytopenia?
Leucocytosis - >50
Leucopenia - <18
The automated analyser total for WBC is usually accurate. When might it be inaccurate and require manual counting?
Many nucleated RBCs (detects as WBCs)
WBC clumped in a clot (still inaccurate if manual count)
Where should a differential WBC count be performed on a blood spear? What pattern is used?
Monocyte layer - feathered edge cells not intact
Battlement pattern - make sure to calculate full blood count as may seem normal until scaled up
What abnormal WBCs are seen with acute inflammation?
Neutrophiliia
Band neutrophils
Lymphopenia
What abnormal WBCs are seen with chronic inflammation?
Neutrophilia
Monocytosis
What can cause neutropenia?
Severe inflammation - sepsis, endotoxaemia, tumour necrosis, bone marrow disease
Also cows with acute inflammation
What is a stress leucogram?
Stress or prolonged steroids in blood causes: L - lymphocytopenia E - eosinopenia M - monocytosis N - neutrophilia (LEMoN)
What is left shift?
Increased number of immature neutrophils (band cells or earlier) released from bone marrow
What causes left shift?
Severe, acute inflammation
What may marked lymphocytosis indicate?
Leukaemia
What causes eosinophilia and basophilia?
Parasitic disease
Allergy
Type I hypersensitivity
What is toxic change? What does it suggest?
Increased blue colour of WBCs
Intense myelopoiesis stimulation - don’t have time to mature
Describe megakaryocytes size and nuclear
LARGE
Lobated nuclei
What are giant platelets? What do they suggest?
Platelets larger than RBCs
Increased thrombopoiesis
Platelet clumps are common in feline and bovine blood samples. Why?
Slow/poor venepuncture,
Inadequate mixing with anti-coagulant
Hyperactive platelet
What can cause thrombocytopenia?
Increased destruction - immune-mediated thrombocytopenia (autoimmune or idiopathic)
Increased consumption
Decreased production
Redistribution
What could cause redistribution of platelets and thrombocytopenia?
Splenic torsion, splenomegaly
What clinical signs may be seen with severe thrombocytopenia?
Petechia, purpura, ecchymoses
Epistaxis (nose bleed)
Melaena and haematochezia
Haematouria
What does moderate and severe thrombocytosis indicate?
Moderate - no clinical significance, common
Severe- chronic bleeding, inflammation, iron deficiency
