Leukocytes Flashcards
What makes up a complete blood count?
Leukogram
Erythrogram
Thrombogram
What is a leukogram?
Evaluation of leukocytes
What is an ertythrogram?
Evaluation of erythrocytes
What is a thrombogram?
Evaluation of platelets
What does it mean if the results of a CBC are within the reference interval?
Minimal effect of disease
What does it meant if the CBC shows increased cell concentration?
Increased production
Shift from SP or other non-circulating pool to CP
Increased blood life span
What does it mean if the CBC shows decreased cell concentration (cytopenia)?
Decreased production
CP to non-circulating pool
Decreased life span
What should the CBC blood sample be like?
K2EDTA, K3EDTA (purple top)
No clots or platelet clumps
Several hours RT or 24 hours in refrigerator at 4C
Describe microscopic evaluation
Always a part of CBC
Blood film with 4 parts: blood drop site, thick area, monolayer, feathered edge
What is the most important art of blood film?
Monolayer
Describe the monolayer?
Erythrocytes occasionally touch each other and leukocytes’ nuclear and cytoplasmic features are visible
What is stained with a romanowsky stain?
Acidic structures (basophilic/blue): DNA and RNA Alkaline structures (eosiniophilic/red): hemoglobin and eosinophil granules
What are the descriptive terms used with a romanowsky stain?
Neutrophilic
Eosinophilic
Basophilic
Azurophilic
What are ways to determine leukocyte concentration?
Impedance and flow cytometer counters
Describe impedance counters
A current that passes from cathode to anode. Cells disrupt the current when it passes through there and once it happens you can count how many cells pass and measure size
Describe flow cytometer counters
Cells passes through a laser which heats the cell. It will heat the things inside the cells and scatter the light. This can tell a cell apart by the presence of light and how it changes the trajectory. It can also tell how much of something is inside a cell
Do we use relative or absolute changes?
We use absolute. Relative changes may not reflect true changes
Where are most leukocytes produced?
In the bone marrow
What will you see if the bone marrow isn’t producing a lot of cells?
More adipose cells
What are the leukocytes in tissues?
Granulocytes (netrophils, eosinophils, basophils)
Lymphocytes
Monocytes (histiocytes or macrophages)
Mast cells
What is the function of granulocytes?
Defense and die
What is the function of lymphocytes?
Blastogenesis, return to blood, or die
What is the function of monocytes?
Defense and die
What is the function of mast cells?
Defense and die
What is blastogenesis?
Transformation of small lymphocytes of peripheral blood into cells capable of undergoing mitosis
Describe the process of neutrophil maturation
Myeloblast Promyelocyte Myelocyte Metamyelocyte Band Neutrophil Hypersegmented
What are the leukocytes pools?
Production pool (ProNP) Maturation pool (MatNP) Storage pool (SNP) Circulating pool (CNP) Marginating pool (MNP) Tissue
What pools are in the bone marrow?
ProNP
MatNP
SNP
What pools are in the blood?
CNP (free flowing)
MNP (adhered)
What pool are you taking from when you get a blood sample?
Circulating
What regulates neutrophil production?
IL-1 IL-3 IL-6 GM-CSF G-CSF
What chemoattractants cause the release of neutrophils?
C5a
IL-8
LTB4
PAF
What cytokines cause the release of neutrophils?
IL-1 IL-6 TNFα TNFβ G-CSF GM-CSF
What is the half life on neutrophils in the blood?
5-10 hours
What is the ratio of CNP:MNP in the blood?
1: 1 for most mammals
3: 1 for cats
What contributes to blood neutrophil concentration?
Production
Release
CNP:MNP
Migration to tissue
What causes neutrophils to migrate to tissues?
C5a
IL-8
LTB4
PAF
What is a left shift in neutrophil concentration?
Increase of non-segmented neutrophils in the blood
Above the reference interval
What is a left shift in neutrophil concentration the hallmark of?
Acute inflammation
What are common causes of a left shift?
Steroids and endotoxin
Describe the left shift severity classification
Bands: mild, 1000/μL
Bands and metamyelocytes: moderate, 1000-10,000/μL
Bands, metamyelocytes, and myelocytes: marked, more than 10,000/μL
What qualifies as a degenerative left shift?
Non-segmented neutrophils greater than segmented neutrophils
Segmented neutrophils is less than the reference interval
What qualifies as a regenerative left shift?
Segmented neutrophils are greater than the reference interval and segmented neutrophil is greater than non-segmented
Segmented within the reference interval is not classified
Which has a better prognosis, degenerative or regenerative left shift?
Regenerative
What is the clinical relevance of a left shift?
Prognostic tool
Regenerative: adequate response to the inflammatory process
Degenerative: inadequate response
What is a right shift in the neutrophil concentration?
Increased numbers of hypersegmented neutrophils (5 or more segmentations)
What is the most common cause of a right shift?
Glucocorticoid hormones (endogenous and exogenous)
What indicates neutrophilia/acute inflammation?
Inflammatory mediators
Increase CNP (may contain bands)
Release of SNP occurs in hours
Release of MatNP occurs after depletion of SNP
Increased production from stem cells, 5 days
Why are mediators necessary in acute inflammation?
To increase the release of neutrophils
What does the magnitude of neutrophilia depend on?
Species
What is the leukemoid response?
Occurs with neutrophilia/acute inflammation
Looks like leukemia but is proven not to be
What is unique about bovine and the SNP?
It is small, so you need to increase production
Describe neutrophilia/chronic inflammation
Inflammation after at least a week
Replenishment of SNP: release of segs, not bands
Less severe neutrophilia
With persistent intense stimulus, acute inflammatory response continues
Describe neutrophilia due to steroid (stress)
Endogenous or exogenous glucocorticoids
Shift from MNP to CNP
Doubles (canine, equine, bovine), greater in felines
Decreased emigration to tissues, increased circulating life span
Increased release from BM: mostly mature, but also bands
Most frequently seen in dogs (neutrophilia, monocytosis, lymphopenia, and eosinopenia)
Left shift (less than 1000/μL), right shift, or no shift
Describe neutrophilia due to physiologic shift
Catecholamines Shift from MNP to CNP Doubles for dogs, horses, and cattle, triplicate or quadruplicate for feline Frequently in healthy animals Back to "normal" in 60 minutes May increase lymphocytes numbers too
Describe neutrophilia due to chronic myeloid leukemia
Clonoal proliferation
Mature (segmented) neutrophils
Difficult to differentiate from extreme neutrophilia
Describe neutrophilia that is paraneoplastic
Neoplastic cells can produce G-CSF or a similar substance
Adenomatous polyp, renal tubular carcinoma, metastatic fibrosarcoma
What are some other causes of neutrophilia?
Leukocyte adhesion deficiency from a lack of CD18
G-CSF administration
Estrogen toxicosis
What is the main cause of neutropenia?
Overwhelming inflammation
Describe neutropenia due to inflammation
Migration exceeds release
Mediators also cause increased production but it will take at least 2 days to see blood changes
SNP is released first, then MatNP; if migration is too severe left shift then it may not be present (bands migrating fast too)
Common in cattle because the have a small SNP
Describe neutropenia due to endotoxemia
Margination of neutrophils
Duration is 1 to 3 hours
Stimulate release from BM in 8 to 12 hours
Stimulate production: 3-5 days
Describe neutropenia due to immune-mediated peripheral destruction
Ab binds to neutrophils
Destruction by mononuclear phagocyte system
May be responsive to glucocorticoid treatment
May see granulocytic hyperplasia in BM
Describe neutropenia due to peripheral destruction from hemophagocytic syndrome
Phagocyte hyperplasia
May see other cytopenias
In people, it is secondary to infections and neoplastic cells
What is the size of small lymphocytes compared to erythrocytes?
1 to 1.5 erythrocytes
What is the size of medium lymphocytes compared to erythrocytes?
1.5 to 2 erythrocytes
What is the size of large lymphocytes compared to erythrocytes?
More than 2 erythrocytes
What are the lymphocytes in the blood?
Most are T lymphocytes
CLP and MLP
What happens to lymphocytes in lymph nodes?
Enter cortices via specialized postcapillary venules
Exit via efferent lymphatic vessels
25% enter lymph nodes each day
What happens to lymphocytes in the tissue?
Blastogenesis, recirculate, or die
Migration from vessels to tissue similar to neutrophils
What is the blood concentration of lymphocytes?
Production (stem cell or blastogenesis)
CLP and MLP
Life span is hours to years
Describe lymphocytosis due to chronic inflammation
Chronic antigenic or cytokine stimulus Reactive lymphocytes may be present Enlarged lymph nodes or lymphoid organs Mild to moderate Neutrophilia, monocytosis
Describe lymphocytosis due to physiologuc shift
Catecholamines MLP to CLP 2 x URL Minutes to hours No morphologic change May cause large granular lymphocytes to increase
Describe lymphocytosis due to lymphoproliferative disease
Neoplastic proliferation
Lymph nodes, BM, other tissues
BLV and FeLV
Leukemia may be leukemic manifestation of lymphoma
Leukemia: marked lymphocytosis with cells displaying immature features
Describe lymphocytosis dues to hypoadrenocorticism
Lack of glucocorticoids
Dogs: neutropenia with lymphocytosis and azotemia
May also see high normal to mild eosiniophilia
Describe lymphocytosis in young animals
Cattle: increases until 1 year old and then gradually decreases
Up to 2 URL
Describe lymphopenia due to acute inflammation
Change in lymphocyte kinetic decreasing CLP
It my be caused by stress
Describe lymphopenia due to steroids/stress
Change in lymphocyte kinetics decreasing CLP
Endogenous and exogenous glucocorticoids
Immediate shift from CLP to other pools. May be entrapped in lymph nodes or BM
Later lymphotoxic effects leading to lymphoid hypoplasia
What is the most common cause of lymphopenia?
Steroids/stress
Describe lymphopenia due to depletion
Loss of lymphocytes due to incomplete circulation
Repeated chylothoracic fluid removal in cats
Describe lymphopenia die to lymphoid hypoplasia or aplasia
Congenital or acquired
Decrease lymphocyte production
Selective T lymphocyte hypoplasia or aplasia will cause more severe lymphopenia than selective B lymphocyte hypoplasia or aplasia
Describe lymohopenia due to lymphoma
Common in animals with lymphoma
Decrease production or altered kinetics
What are monocytes produced from?
Stem cells: CFU-GM (granulocytes)
What pools are avaiable in the vessel for monocytes?
CMP and MMP
What happens once monocytes get to the tissue?
They form the mononuclear phagocyte system
What makes up the mononuclear phagocyte system?
Macrophages
Microglial cells
Dendritic cells
Describe monocytosis due to inflammation
Acute and chronic inflammation
Cytokine stimulation: production and release
Describe monocytosis due to steroids/stress
Common in dogs and cats, minimal in horses and cattle
Shift from MMP to CMP
Describe monocytosis due to neoplastic cells
Monocytic leukemia
Marked monocytosis
Normal and abnormal monocytes
Uncommon when compared to granulocytic and lymphoid leukemias
Describe monocytosis that is secondary to immune-mediated neutropenia
Monocytes and neutrophils share common progenitor
May increase monocytopoiesis when stimulating neutropoiesis
Describe monocytosis due to cyclic hematopoiesis
Mild during neutropenic cycles
Herald increase neutrophil concentration
Describe monocytosis due to G-CSF treatment
Increase production of neutrophils and monocytes
Why is monocytopenia difficult to document?
The lower reference limit is already very low for monocyte concentration, but it is not considered a diagnostic problem
What causes differentiation with eosinophils?
IL-5
GM-CSF
What are the pools for eosinophils in the blood?
CEP and MEP (minutes to hours in the blood)
What do eosinophils do in the tissue?
Bactericidal properties
Inactivate mast cell mediators
Attack parasite larvae and adult stages
What is eosinophilia due to?
Anti-inflammatory function Attraction after mast cells or basophil degranulation Hypersensitivity Internal and external parasites Inflammation in mast cells rich tissues Occasionally in hypoadrenocorticism
Describe eosinophilia due to idiopathic hypereosinophilic syndrome
Cats, dogs, horses
Persistent marked eosinophilia without apparent cause
No features suggestive of leukemia
Hypereosinophili: more than 20,000/μL
Describe eosinophilia due to paraneoplastic effects
Mast cell neoplasms
Other neoplasms that can release IL-5
Dogs: T cell lymphoma, thymoma, mammary carcinoma, oral fibrosarcoma, and rectal adenomatous polyp
Cats: TCC, T cell lymphoma, and alimentary lymphoma
Horses: intestinal lymphomas
When should basophilia be considered?
When it is persistently above 200 to 300 μL
What are causes of basophilia?
Allergic, parasitic, and neoplastic states
Why is a basopenia hard to documaent?
There is already a very low LRL for basophil concentration, but it is not known to be clinically relevant
What are toxic neutrophils?
Neutrophils with toxic changes
What are examples of toxic changes?
Foamy cytoplasm
Diffuse cytoplasmic basophilia
Dohle’s bodies
Giant neutrophils
What is a foamy cytoplasm?
Cytoplasmic clearing due to dispersed organelles
What is diffuse cytoplasmic basophilia?
Retention of RNA during maturation
Segmented neutrophils should not have this, so when they do, it is considered a toxic change
A normal band will have this
What are Dohle’s bodies?
Aggregates of rough endoplasmic reticulum
What are giant neutrophils?
Larger neutrophils due to asynchronous maturation
What do toxic changes represent?
Maturation defects caused by rapid neutropoiesis
What are hypersegmented neutrophils?
More than 5 lobes
Typically old neutrophils
Myelodysplastic syndromes involving neutrophilic cell line
Found in Poodle marrow dyscrasia
What can reactive lymphocytes be found in?
Acute and chronic inflammation
What can reactive lymphocytes be difficult to differentaite from?
Atypical (neoplastic) lymphocytes
Describe monocytes that have features of macrophages
Abdundant gray cytoplasm
With or without vacuolation
Seen in systemic infections (histoplasmosis, ehrlichiosis, babesiosis, or leishimaiasis)
Describe sideroleukocytes
Neutrophil or monocyte containing hemosiderin
Rare, but can be seen with hemolytic anemias and after transfusions
Describe erythrophage
Neutrophil or macrophages with phagocytized erythrocyte Occasionally seen with IMHA Idiopathic immune-mediated anemia dogs Equine infectious anemia Neonatal isoerytholysis
Describe lupus erythematosus (LE) cells
Neutrophil that phagocytized nuclear antigen-antibody complexes
Pink to palke basophilic inclusion of variable sizes
Describe bacteria not from the family Anaplasmacetae in leukocytes
Rare in patients with bacteremia
Bacteria in blood; can be true bacteremia, can be contamination of the sample
Describe bacteria from the family Anaplasmacetae in leukocytes
Can invade and multiply in blood leukocytes
Monocytic ones tend to be more species specific
Leukocytic ones are less specific
Describe canine distemper inclusions in leukocytes
Monomorphic or polymorphic
Red to purplish red or pale blue
Neutrophils, monocytes, lymphocytes, and erythrocytes
Describe Hepatozoon americanum in leukocytes
Gametocytes infect neutrophils and monocytes
Describe Hepatozoon canis
Gametocytes infect neutrophils and monocytes
Found in Europe, Asia, Africa, and South America
Lack obvious clinical signs
Describe Histoplasma capsulatum in leukocytes
Single or multiple in the cytoplasm f neutrophils, monocytes, or eosinophils
Yeasat phase
2 to 4 μm
Eccentric basophilic region with nuclear material
Describe Leishmania in leukocytes
Kinetoplastid protozoan found primarily in the Mediterranean, central and South American countries
Found in Ohio, Oklahoma, and SE US
Amastigotes found in macrophages
Describe Mycobacterium in leukocytes
Rarely seen systemic
Can be seen in neutrophils or monocytes
Won’t stain with Wright stain
Describe Toxolasma gondii in leukocytes
Tachzoites are rarely found in blood neutrophils and monocytes
More common in macrophages of infected organs
Describe leukocyte adhesion deficiency (LAD)
Irish red and white setters, Holstein cattle
Canine LAD (CLAD) and Bovine LAD (BLAD)
Defects in the integrin CD18
No functional CD11/CD18
Necessary for adherence, migration, and aggreagation
Describe CLAD
Persistent leukocytosis and granulocytic hyperplasia in the BM
Susceptible to infections
PCR diagnosis
Describe BLAD
Marked neutrophilia and recurrent infection
PCR diagnosis
Describe the Pelger-Huet anomaly
Several breeds of dogs, DSH cats, and Arabians
Hyposegmentaion of neutrophils, eosinophils, and basophils
Nuclear chromatin: hyperchomatic or normochromatic
These are not bands because the bands with this anomaly are very condensed rater than more open-faced
What are psuedo pelger-huet neutrophils found in?
Cows, dogs with severe inflammation, and cats wuth FeLV myeloid leukemia
What are psuedo pelger-huet eosinophils found in?
Cattle and horses (with neutrophils)
Describe nonstaining eosinophil granules (gray eosinophil) of dogs
Greyhounds, Golden retrievers, Shetland sheepdog
Poor staining eosinophil granules or just the vacuoles and gray cytoplasm
Modified chemical composition
No pathological significance
Maybe misclassified by counters (ADVIA)
