Table 1 . Types of leucocytes .
Type Description Role
Possible causes of elevated levels
Possible causes of decreased levels
Neutrophils
Eosinophils
Basophils
Multi-lobed purplestaining nucleus . Pale grey cytoplasm , sometimes with pink granules
Pink rod-shaped granules . Segmented nucleus
Irregular nucleus with blue granular cytoplasm
Lymphocytes Smallest white blood cell . Circular to cleaved or indented nucleus . Small amount of light blue cytoplasm
Monocytes
Horseshoe-shaped nucleus . The largest white blood cell with a light blue nucleus . Often vacuolated
Phagocytosis
Parasitic response
Allergic response
Immune response
Neutrophilia – bacterial infection , inflammation , stress or neoplasia
Eosinophilia – allergic reactions or parasitic infections
Basophilia – rare but can be seen with allergic and parasitic responses or neoplasia
Lymphocytosis – chronic disease , exercise , stress , lymphoproliferative disease
Phagocytosis Monocytosis – infection , inflammation , stress , steroids and immune-mediated conditions
Neutropenia – viral infections , cytotoxic medication , bone marrow disorders
Eosinopenia – steroid therapy
Basopenia – very rare
Lymphopenia – viral disease , steroid therapy
Monocytopenia – rare
Figure 8 . Platelet clumps . Figure 9 . Giant platelets .
Estimating platelet numbers
To estimate platelet numbers , using a × 100 oil immersion lens , begin by counting all of the platelets seen in 10 HPF . Add the numbers together and divide by 10 , to give the average . Multiply the average by 15 . The result will represent the count in × 10 9 / l .
Conclusions
Haematology should be two-fold , with automated analysis used alongside examination of a blood film to obtain the most relevant clinical data . The field of haematology is vast , but that should not deter us from gaining experience of looking at blood films under a microscope .
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