WBC differential count

Objective

• In the normal blood film, up to five different types of normal WBC can be seen. They are Neutrophils (stab and polymorphs), Lymphocytes, Monocytes and Basophils.

• In disease either the percent of normal WBC is disturbed, or/and abnormal and immature WBC are seen in a peripheral blood films.

• The object of differential WBC count is to determine the percentage of each type of WBC from a stained blood film.

Differential white blood cells count (normal adult)

Absolute Values Percentage.

Neutrophil 2.0-7.0 x109/L 40-75 %

Lymphocytes 1.0-3.0 x109/L 20-45 %

Monocytes 0.2-1.0 x109/L 2-10 %

Eosinophil 0.02-0.5 x109/L 1-6 %

Basophile 0.02-0.1 x109/L 0-2 %

Normal neutrophil and monocyte

Neutrophils are similar in most domestic species, characterised by pale cytoplasm and dark nucleus segmented into 2-5 lobes, although granules are more readily seen in ruminants.

Monocytes are similar in most species; large cells with basophilic cytoplasm (often vacuolated or with tiny pink granules), and a pale irregularly clefted or folded nucleus with clumped chromatin.

Normal eosinophil and basophil

Morphology of eosinophils varies widely with species; granules are large in horses, small & numerous in ruminants, accompanied by vacuoles in dogs, and rod-shaped in cats

Basophils have purple-black granules, are numerous in large animals and may be almost absent in healthy dogs and cats.

Lymphocyte

Small regular cells. The nucleus is regular staining deep dark violet with condensed chromatin. The nucleus is not segmented and is filling most of the cytoplasm. Cytoplasm stains deep blue.

Large cell (about 22 microns) with violet colored nucleus with less condensed chromatin. The cytoplasm is abundant and stains blue and sometimes few fine granules are seen.