LEUKOCYTE EVALUATION
Clinical Textbook for Veterinary Technicians 4th edition Dennis M. McCurnin Suanders
WBCs are categorized as
1) granulocytes (neutrophils, eosinophils, basophils)
* characterized by segmented (lobed) nuclei and
expect for the neutrophil, distinct cytoplamsmic
granules
Or
2) agranulocytes (lymphocytes, monocytes)
* also referred to as monocuclear cells and do not
have segmented nuclei
Neutrophils: the predominant WBC
* phagocytic
* bacteriocidal
* important in inflammatory conditions
The average time spent by a neutrophil in the blood is about 10
hours.
Normal neutrophils have deeply staining, clumped, segmented
nuclei with relatively clear cytoplasm (sometimes a faint dusting
of granules)
Segmented Neutrophils
Morphological changes in the neutrophil:
Bands – appearance of band shaped nuclei indicated the
release of immature neutrophils
Even more immature neutrophils have oval or bean shaped
nuclei.
Neutrophils may show signs of inflammatory disease as
demonstrated by certain cytoplasmic characteristics:
•Toxic neutrophils –
Dohle bodies – small, pale bluish-gray irregular inclusions
in the cytoplasm that usually indicate mild toxemia.
Generalized basophilia of the cytoplasm or cytoplasmic
vacuolation are slightly more severe toxic changes.
Neutrophilia – increased number of total neutrophils.
Neutropenia – a decrease in circulating neutrophils. May occur
when tissue demand is excessive as a result of severe inflammation
exceeding the ability of the bone marrow to supply the cells.
Eosinophils
* help control allergic or anaphylactic hypersensitivity
reactions
The eosinophil is characterized by a segmented nucleus, colorless to
pale-blue cytoplasm and distinct eosinophilic (reddish-orange)
staining granules in the cytoplasm
Eosinophils Per species:
Cats – contain numerous tiny rod-shaped granules that may
obscure the nucleus
Dogs – granules are less numerous and usually round but may vary
considerably in size.
Horses – granules are extremely distinctive, being very large and
round and a much brighter orange than smaller animals
Bovine – granules are also bright orange but are much smaller and
more numerous than those of the horse.
Basophils
Relatively rare in blood smears.
When they do appear they tend to occur in association with
increased eosinophils.
They have dark basophilic (blue) granules.
Basophils per species:
Cats – granules tend to be light lavender to almost pink
Dogs – have few to no granules and must be differentiated from
neutrophils.
Equine and Bovine – tend to have variable numbers of more typical
dark granules
Lymphocytes
Usually small to medium sized mononuclear cells with a thin rim
of light to dark-blue cytoplasm and a round nucleus.
The cytoplasm may or may not contain red granules.
Monocytes
•Derived from bone marrow
•Circulate in the blood briefly before entering the tissues in
which they become macrophages
Phagocytize large particles and cellular debris that
neutrophils cannot handle.
Monoctyes have gray-blue, often grainy cytoplasm and a variable
shaped nucleus.