Leukocyte identification and evaluation Flashcards
Leukocyte identification
Identification of white blood cells found in the peripheral blood
A leukogram- is the quantification of the different classes of leukocytes as well as ny morphologic abnormalities of the cells
Calculated by evaluating a peripheral blood smear
Species differences
How to examine a blood smear
Start by examining th slide on the 40x objective
-Examine the slide for platelet clumps, enlarged cells and microfilariae
Go to the feathered edge of the slide
-Look for evidence of platelet or cell clumping
Move 3-4 fields inwards to the monolayer
-This is where you will find approx. 200 cells/field
-Cells are single layer→ they are not overlapping and they are not touching
Go to 100x objective
-Perform the differential cell count
-100 WBC will be counted- this will give you a percentage for each cell type observed
Absolute values
Once your differential cell count is performed and your total WBC count is known, absolute values of the WBCs can be calculated
Neutrophils are
Also known as “segs”
Nucleus: irregular, elongated and lobed
Segmented neutrophils
Mature neutrophil- the most abundant leukocyte in peripheral blood in small animals
Granulocytic cell
What do neutrophils do
Participate in the inflammatory response
Increased numbers generally indicate inflammation of infection
Phagocytosis of foreign invaders or disease self
what do neutrophils look like
Small, very poorly stained granules
species/individual differences: colourless to lightly staining granules
Cattle- granules stain faintly pink, giving cytoplasm an orange-pink tint overall
Horses- fine diffuse granules
May contain small vacuoles, cells will be larger if they are actively phagocytic
Larger cells may have a bubbly or foamy appearance
Reptile, birds, some fish and some mammals (rabbits and guinea pigs) have heterophils in the place of neutrophils
Granules are eosinophilic
Band neutrophils are and look like
Immature stage of neutrophils
Has a smooth, parallel sided, horseshoe-shaped nucleus with “clubbed ends” and no constrictions, the chromatin is visible
If the narrowest part of the nucleus is greater than ⅔ the width of the widest part of the nucleus, the cell is classified as a band neutrophil
When unsure of what maturity stage a cell is, always classify it as the more mature stage
Normal values for all species: 0-3%
Eosinophils are and function
Granulocytic cell
Nucleus similar to neutrophils
Primary function is in immune system modulation
Also capable of phagocytosis
Numbers increase with allergic reaction and parasitic infections
Found in small numbers in peripheral blood in healthy animals
What do eosinophils look look
Contain granules that are large and stain red
They vary considerably b/w species
Canine: granules are light reddish colour and will range from small to large within the same cell, 2-10%
Feline: granules are rod-shaped, small, numerous and stain a reddish colour, 2-12%
Equine: bright orange-red granules are very large, often filling the cell and occluding the nucleus, 0-4%
Bovine: granules are relatively small, round and red, 2-20%
Basophils are and functions
Granulocytic cell
Involved in the deviation of immune system
Will see increased numbers with inflammation or infection
Not often found in peripheral blood smears
Basophils look like
They are larger than neutrophils
Have nucleus similar to monocytes
They have granules that vary among species
Canine: small number of dark- purple-blue/black granules
Feline: large, round, lavender granules
Equine/Bovine: large number of dark blue/black granules that may contain the nucleus (0-3%
Lymphocytes are and function
Agranulocytic cell
Function is the humoral immune response (fever, etc) and cell mediated responses (antibody production)
Lymphocytes look like
Dark purple- blue round to oval or slightly indented nucleus (kidney bean shape)
The nucleus will have variations of its colour due to the clumping of chromatin
Small amount of clear to sky blue cytoplasm, may appear to have none
Most abundant cell in the blood smear of ruminants
Variation in lymphocyte size based on species
Cats and dogs have smaller lymphocytes with scant cytoplasm
Cattle have medium to large (neutrophil size) lymphocytes with more abundant cytoplasm
Cytoplasm may have pink/purple granules
What does an increase of lymphocytes indicate
Viral infection
Monocytes are and functions
Classified as agranulocytes cells
The largest of the WBCs
Participate in the inflammatory response
Numbers are often increased with chronic infections
Capable of migrating into tissues
They phagocytize foreign material and dead, dying or diseased cells
Responsible for normal erythrocyte destruction and associated metabolic iron recycling
The most misidentified cell on blood smears
Monocyte looks like
Nucleus varies in shape, but is generally kidney shaped with occasional lobes
A soft cell, so it can fold over on itself- giving it weird shapes
Nucleus does not stain as dark as other cells and appears to have a lacy appearance
Cytoplasm is grey-blue
The cytoplasm may contain small, pink granules or vacuoles
Monocyte identification
Cytoplasm is grey-blue with ground glass appearance, sometimes tiny pink granules
Nucleus is usually deeply indented and may show amoeboid characteristics
Large and small vacuoles may be preset
Chromatin (in the nucleus) is reticulated (lacy)
Lymphocyte identification
Cytoplasm is true or sky-blue no granules except the occasional large one
Nucleus is round to slightly indented (occasional deep indentation)
Vacuoles are extremely rare and are tiny if present
Chromatin is clumped
2 systems used to identify abnormal leukocyte morphology
Slight, moderate, marked
Slight: ~10% of cells affected
Moderate :~25% of cells affected
Marked: >50% of cells affected
1+,2+,3+,4+
1+: 5-10% of cells affected
2+: 10-25% of cells affected
3+: ~50% of cells affected
4+: >75% of cells affected
Abnormal leukocyte morphology
Nuclear hypersegmentation
Toxic change
Intracytoplasmic inclusions
Atypical and reactive lymphocytes
Smudge cells/basket cells
Neoplasia
Nuclear hypersegmentation is
Canine or feline neutrophils with more than 5 lobes
Usually due to ageing of cells either in the patient or in the blood tube
Commonly seen
Toxic change of leukocytes is
The most common disease-induced cytoplasmic change in neutrophils
Found in association with inflammation, infection and drug toxicity
If severe, it is often in association with a bacterial infection
Most significant when found in dogs
Common in cats that are not severely ill
Cytoplasmic basophilia
What can be seen in leukocytes with toxic change
Cytoplasmic basophilia
Dohle bodies
Blue staining cytoplasmic inclusions
Can be single or multiples
Vacuoles or “foamy” appearance to the cytoplasm
Toxic granulation (rare)
Intensely stained granules
May be significantly larger than normal neutrophils
