6. Leukocyte Identification and Evaluation Flashcards
(37 cards)
What is leukocyte identification? What is a leukogram
id of WBC’s found in the perpheral blood
A leukogram - is the quantification of the diff classes of leukocytes as well as any morphologic abnormalities of the cells - calculated by evaluating a peripheral blood smear, species differences
How do we examine a blood smear
- start by examining on 40x objective for platelet clumps, enlarged cells and microfilariae
- go to feathered edge of slide for platelet or cell clumping
- Move 3-4 fields inwards to the monolayer where you’ll fine approx 200 cells/field, cells are single layer, they are not overlapping and they are not touching
- Go to 100x objective and perform differential cell count, 100 WBC will be counted to give % for each cell type observed
What are absolute values
once your differential cell count is performed and your total WBC count is known, absolute values of the wbc’s can be calculated
For absolute values, if the total WBC count is 4.4x10^9/L and differential count is as follows
neutrophils: 49% x4.4x10^9/L = 2.2x10^9/L
Lymphocytes: 44% x 4.4x10^9/L = 1.9x10^9/L
Monocytes: 2% = 0.1x10^9/L
Eosinophils: 5% = 0.2x10^9/L
Basophils: 0% = 0.0x10^9/L
What do neutrophils look like
aka “segs”
Nucleus: irregular, elongted and lobed
Segmented neutrophil - mature neutrophil is the most abundant leukocyte in peripheral blood in SA, granulocytic cell
Small, very poorly stained granules
may contain small vacuoles, cells will be larger if actively phagocytic
What is the neutrophils job?
Participate in the inflam response with an inc # generally indicate inflam or infection
Phagocytosis of foreign invaders or diseased self
Do all neutrophils across the species look the same? If not, what are the differences
Cattle - granules stain faintly pink, giving cytoplasm an orange-pink tint overall
Horses - fine diffuse granules
Reptiles, birds, some fish and some small mammals like rabbits and guinea pigs have heterophils in the place of neutrophils (granules are eosinophilic)
What are band neutrophils
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 is 2/3 the sides of the widest part of the nucleus = band beutro
When unsure, always class as more mature stage
Normal values for all species 0-3%
What are eosinophils?
granulocytic cell, nucleus similar to neutrophils
primary func is in immune system modulation - capable of phagocytosis, #’s inc w/ allergic reactions and parasitic infections
Found in sm #’s in peripheral blood in healthy animals
Contain granules that are large and stain red - vary considerably btw species
How do the granules of k9, fel, equine and bovine differ?
k(: granules light reddish color and will range from sm-lg within same cell 2-10%
Feline : granules are rod-shapped, sm, numerous and stain a reddish color 2-12%
Equine : bright orange-red granules are very lg, often filling the cell and occluding the nucleus 0-4%
Bovine: granules are relatively sm, round and red 2-20%
What are basophils and what do they do?
involved in the mediation of the immune system - will see inc #’s w/ inflam or infection
not often found in peripheral blood smears - larger than neutrophils, have a nucleus similar to monocytes
What are the differences of basophils btw k9, feel, eq and bovine
K9 - small # of dark - purple-blue/black granules
Feline: Large, round, lavender granules
Equine/Bovine: large number of dark blue/granules that may occlude the nucleus (0-3%)
What are lymphocytes and what do they do?
Agranulocytic cell, func in the humoral immune response (fever) & cell mediated responses (antibody production)
Most abundant cell in blood smear of ruminants
an inc in lymphocytes usually indicates viral infection
What do lymphocytes look like?
dark purple/blue round to oval or slightly indented nucleus (bean)
nucleus will have variations of color due to clumping of chromatin
sm amount of clear to sky blue cytoplasm, may appear to have none
k9/cats have smler lymphocyte with scant cytoplasm
cattle have med to large (neutrophil size) lymphocytes with more abundant cytoplasm - pink/purple granules)
What are monocytes?
Classed as agranulocytic cells
largest of the WBC’s, participate in the inflame response - numbers are often inc w/ chronic infections
capable of migrating into tissues(become macrophages)
then phagocytize foreign material and dead, dying or dz’d cells
responsible for normal erythrocyte destruction and associated metabolic iron recycling
What is the most misidentified cell on blood smears and why?
nucleus varies in shape, generally bean shaped with occasional lobes
a soft cell, so can fold over itself
nucleus does not stain as dark as other cells and appears to have a lacy appearance
cytoplasm is grey-blue and may contain some small, pink granules or vacuoles
How can you tell a monocyte from a lymphocyte in LA?
Monocyte - cytoplasm grey/blue, ground glass appearance, tiny pink granules
Nucleus deeply indented, maybe amoeboid traits
Large/sm vacuoles maybe present
chromatic is reticulated (lacy)
LYMPHO - cytoplasm trye or sky-blue, no granules except occasional large one. Nucleus round to slightly indented, vacuoles are extremely rare and are tiny if present, chromatin is clumped
How do we quantify abnormal morphology? What is the system we will be using in lab?
Subjective assessment, 2 systems
1. Slight: ~10% of cells affected
Moderate: ~25% of cells affected
Marked: >50% of cells affected
2. 1+: 5-10% of cells affected
2+: 10-25% of cells affected
3+: ~50% of cells affected
4+: >75% of cells affected
What might happen with abnormal leukocyte morphology?
nuclear hypersegmentation
toxic change
intracytoplasmic inclusions
atypical and reactive lymphocytes
smudge cells/basket cells
neoplasia
What is nuclear hypersegmentation?
canine or feline neutrophils with >5 lobes
usually due to aging of cells either in the patient or in the blood tube
What is toxic change in cells?
most common dz-induced cytoplasmic change in neutrophils
found in association w/ inflam, infection and drug toxicity - if severe, often associated w/ bact infection
Significant in dogs, common in cats
What happens with toxic change?
cytoplasmic basophilia
Dohle doies - blue staining cytoplasm inclusions, single or multiple
Vacuoles or “foamy” appearance to the cytoplasm
Toxic granulation (rare) -intensly stained granules
may be significantly lger than normal neutrophils
How do we quantify toxic change?
slightly diff than quantification of other abnormal WBC morphology
May be based on #’s of cells affected OR observations noted
Through quantifying toxic change, what system do you use when noting percentage of neutrophils with toxic change?
Mild: 5-10%
Moderate: 11-30%
Marked: >30%
