Leukogram Flashcards
What is the difference between -penia and -philia/-cytosis?
decreased concentration of cells (neutropenia, lymphopenia, eosinopenia)
increased concentration of cells (neutrophilia, eosinophilia, basophilia, monocytosis, lymphocytosis)
What is left shift? What does it mean if it’s associated with neutropenia?
increased concentration of immature neutrophils in the blood, usually band neutrophils but can be metamyelocytes
more severe inflammatory response
What is orderly maturation? What does it mean if a left shift is orderly? Disorderly?
concentration of each cell increases with the degree of maturity
there should be more bands than metamyelocytes, and more segmented neutrophils than bands
consumption if very severe or a neoplastic process is present (leukemia)
What is leukemia?
presence of neoplastic cells in the blood or bone marrow with a variable concentration from non-detectable to >500,000 µL
What are lymphoproliferative and myeloproliferative disorders?
LYMPHOPROLIFERATIVE - neoplasms of lymphocytes and plasma cells
MYELOPROLIFERATIVE - neoplasms arising from bone marrow stem cells and involve neutrophils, monocytes, erythrocytes, and rarely eosinophils or basophils
How can analyzers record incorrect total WBC counts? What does this mean?
some analyzers count all nucleated cells as WBCs
- may need a correction factor if there are many nRBCs present
- manual counting by hemocytometer is required for avian/exotics because automated counting will not be reliable with their nRBCs
What are 2 common causes of false decreased WBCs? 3 causes of false increased WBCs?
FALSE DECREASED
1. leukocyte clumping
2. leukocyte lysis common with delayed analysis
FALSE INCREASED
1. abnormally large platelets or platelet clumps
2. high numbers of Heinz bodies
3. high numbers of nRBCs
What are 2 common causes of inaccuracy of WBC from blood smears?
- uneven cell distribution
- poor quality of smear preparation
What WBC information can be reported from automated hematology analyzers? Stained blood smear?
concentrations of each leukocyte type (% and absolute counts)
manual differential counts - a good way to confirm that the instrument is counting cells correctly and evaluate leukocyte morphology and presence of microorganisms
How are manual leukocyte differentials done?
- count 100 WBCs at 50-100x lens with oil
- categorize cells seen (segmented neutrophils, band neutrophils, lymphocytes, eosinophils)
- calculate the percent of each cell out of 100
this is just a % of leukocytes, NOT an absolute
How is the absolute lymphocyte count established?
multiply the % of each leukocyte by the total WBC count
33% lymphocytes, total WBC count - 26,000/µL
= 0.33 x 26,000/µL
= 8,580 µL absolute lymphocyte count
What count is used to interpret WBC results? Why?
ABSOLUTE COUNT, not % —> absolute counts have established reference intervals and are more accurate
WBC leukogram:
What are 3 causes of neutrophilia/heterophilia? What is also seen in these cases?
- PHYSIOLOGIC - lymphocytosis, no left shift
- CORTICOSTEROID-INDUCED (stress) - lymphopenia, no left shift
- INFLAMMATORY - left shift, neutrophil concentration >2x upper limit reference interval
What causes physiologic neutrophilia/heterophilia? What is most commnonly seen with this?
release of epinephrine from fear, excitement, or frisht causes mobilization of marginated neutrophil pools into the circulating neutrophil pool
concurrent lymphocytosis
What does the concurrent lymphocytosis in physiologic neutrophilia/heterophilia cause? In what animals is this most common?
lymphocytes are released from thoracic duct and stay in circulation
more prominent feature in feline excitement response, and seen in horses and cattle
What are 2 causes of stress/corticosteroid neutrophilia/heterophilia? What is most commonly seen with it?
- illness, pain, or metabolic disordered treated with corticosteroids
- corticosteroid-producing tumors
lymphopenia with lymphocytes sequestered in lymphoid tissue
What 2 things are additionally seen in stress/corticoid neutrophilia/heterophilia in dogs?
- eosinopenia
- monocytosis
What is the mechanism of infectious agent-induced inflammatory neutrophilia/heterophilia?
infectious agents stimulate the release of IL, growth factors, and cytokines, which further stimulates granulocytic precursor stem cells in bone marrow to produce more neutrophils
What 2 things are most commonly seen in infectious gent-induced inflammatory neutrophilia/heterophilia?
- left shirt with increased band neutrophils parallel to the degree of inflammation
- greater than 2x upper reference interval
What can happen with severe, overwhelming inflammatory neutrophilia?
rate of neutrophils released from bone marrow is less than the rate of neutrophils used in the tissues —> use > production —> neutropenia
What are the 4 most common patterns seen with inflammatory neutrophilia depending on the severity/type of inflammation?
- mature neutrophilia with a left shift
- mature neutrophilis (>2x upper RI) without left sift
- mature neutropenia with a left shift
- mature neutropenia without a left shift
What are 2 supportive findings having to do with morphology in inflammatory neutrophilia/heterophilia?
- neutrophil toxicity
- reactive lymphocytes
What species has a unique reaction to inflammatory neutrophilia/heterophilia? Why?
CATTLE neutrophils are depleted faster after emigrating to tissues because they have a smaller neutrophil storage pool in bone marrow compared to other species
What cases are considered extreme neutrophilia? What are 5 causes?
> 50,000/µL
- 5 P’s = pyometra, pyothorax, pancreatitis, peritonitis, pneumonia
- leukocyte adhesion deficiency (dog, cattle)
- Hepatozoonosis (dog)
- IMHA
- neoplastic disorders
What are 4 causes of neutropenia/heteropenia?
- endotoxemia
- severe inflammation
- immune-mediated destruction
- decreased production by bone marrow
How does endotoxemia induce neutropenia?
causes the global activation of inflammatory responses, inducing a shift of neutrophil pools from CNP to MNP
How does severe inflammation cause neutropenia? What is it most commonly concurrent with? What are 2 causes?
excessive tissue demand for neutrophils causes the rate of emigration to tissues to exceed the rate of bone marrow production
severe left shift —> neutrophil toxicity/reactive lymphocytes
- endotoxemia
- bacteria
What 4 drugs/toxins are able to decrease bone marrow production of neutrophils?
- radiation
- cytotoxic chemotherapies
- estrogen toxicosis
- bracken fern poisoning
What 3 infectious agents are able to decrease bone marrow production of neutrophils?
- viruses: FeLV, FIV, CPV, FIP
- disseminated fungal infections
- Rickettsial disease
What 3 bone marrow disorders cause a decrease in neutrophil production?
- necrosis
- myelofibrosis
- myelodysplastic syndrome/neoplasia
In what 3 species is physiologic lymphocytosis most common? What mediates it? What is commonly concurrent?
cats, cattle, horses
epinephrine
neutrophilia
What are 3 examples of chronic antigen stimulation lymphocytosis?
- Rocky Mountain spotter fever (Rickettsia rickettsia)
- canine monocytic ehrlichiosis (Ehrlichia canis)
- chronic bacterial, viral, fungal, or parasitic infections
What is the cause of persistent lymphocytosis in cattle? What happens?
bovine leukemia virus infection
virus promotes subclinical, non-neoplastic promotion of B-lymphocyte hyperplasia
How does lymphocytic leukemia look on a blood smear?
presence of different maturation stages of lymphocytes
- lymphoblasts
What is always seen in a stress leukogram? In what animals is this common?
lymphopenia
+ neutrophilia
+ monocytosis
+ eosinophilia
dogs
What 2 infections commonly cause lymphopenia?
- acute viral infections
- bacterial infections
What are 3 common causes of immunodeficiency lymphopenia?
- immunosuppressive therapy or irradiation
- loss of lymphocyte-rich lymph by chylothorax or intestinal lymphangiectasia
- hereditary immunodeficiency, like SCID in foals
What is monocytosis commonly paired with?
neutrophilia in inflammation or corticosteroid-indiced (stress)
What are 7 causes of monocytosis?
- bacteremia
- necrosis
- neoplasia
- hemolysis
- hemorrhage
- immune-mediated disease
- pyogranulomatous disease caused by fungi and parasites
What are 4 causes of eosinophilia? What are some specific examples?
- parasitism
- hypersensitivity
- lesions producing eosinophil chemoattractants, like mast cell tumors
- eosinophilic leukemia
heartworms, hookworms, dermatitis, asthma
What 2 things is basophilia commonly paired with? What are 3 causes?
- eosinophilia
- increased circulating mast cells (mastocytemia)
- allergic/hypersensitivity reactions
- parasitic infections
- basophilic leukemia
What is mastocytemia? In what animals is it most clinically relevant?
increased numbers of mast cells in the blood
cats
What 3 disorders commonly cause mastocytemia?
- reactive inflammatory conditions -enteritis (Parvovirus), pleuritis, and peritonitis
- neoplastic disorders - systemic mast cell disease, progressive from cutaneous or visceral mast cell neoplasia
- mast cell leukemia
Classifying a leukogram:
3 y/o male neutered mixed-breed dog presented with a chronically infected wound on leg.
- Hematology showed erythron and thrombin were WRI
- Blood smear showed RBCs borderline anisocytosis, slight poikilocytosis, and occasionally codocyte present.
- platelets are normal
- neutrophils show basophilic, foamy cytoplasm with prominent Dohle bodies visible
- rare large lymphocytes present
- moderate leukocytosis
- mild neutropenia with a left shift
- mild monocytosis
- neutrophil description is consistent with neutrophil toxicity
matches with an inflammatory leukogram —> increased myelopoiesis and maturation disorders caused by inflammatory mediators
