Leucogram Flashcards
What is the myeloid?
Bone marrow
Outline the development of neutrophils
- In the bone marrow, occasionally extramedullary haematopoiesis (spleen, liver, other)
- Myeloblast -> progranulocyte -> myelocyte -> prolferation and maturation -> metamyelocyte -> band -> segmented neutrophil -> maturation
What is meant by “left shift”?
More immature neutrophils seen
Outline the movement of mature neutrophils to death
- Neutrophil maturation
- Period storage followed by circulation
- Will either be in middle of vessel or towards wall of the vessels (marginated)
- After margination, out of the vessel
- Hypersegmentation and death
What are the steps required for neutrophils to leave blood vessels?
- Marginalisation
- Adhesion
- Migration
What factors may produce a shift from marginal to circulating pool of neutrophils?
- Epinephrine
- Infection
- Stress
What allows the adherence of neutrophils onto cell walls and migration through the wall?
Binding selectin receptors on blood vessels to ligands on cell walls
Compare the proportions of the marginal and circulating pool of neutrophils in the dog and cat
- 50:50 in dogs
- Cat: 25-50% circulating, 50-75% marginal
What is the effect of glucocorticoids on vessel wall adhesion of neutrophils?
Causes neutrophils to stick to walls less i.e. demarginalise and age in the circulating pool
Compare the circulation of lymphocytes and neutrophils
Recirculation occurs with lymphocytes, but not with neutrophils
Compare the appearance of equine lymphocytes to those of dogs
Dogs: small cells with round nuclei, smooth dense chromatin, small rim of blue cytoplasm
- In horse: slightly larger, finer, looser chromatin pattern
Describe the lymphocytes found in ruminants
- variable in appearance
- many are large lymphocytes
- Loosely clumped chromatin
- Fairly abundant cytoplasm
Describe the appearance of reactive lymphocytes
- Larger cells
- Coarse (mature) chromatin
- Deep blue cytoplasm
- Aka immunocytes
Describe the appearance of granular lymphocytes
Distinguished by small pink granules collected into one area of the cytoplasm
What may cause variation in the shape of lymphocytes?
- Mechanical forces applied during smearing
- Molded by contact with red cells
Describe the appearance of feline monocytes
Often look like a “splat” with cytoplasmic vacuolation and some tinge to cytoplasm
What aspects of haematology are included in the erythron?
Red blood cells, haemoglobin, haematocrit/PCV, MCV, MCHC
What aspects of haematology are included in the leukon?
- Total WBC
- Neutrophils
- Lymphocytes
- Monocytes
- Eosinophils
- Basophils
What aspects of haematology are included in the thrombon?
Platelet count
Describe the characteristics of leukocytosis
- Neutrophilia
- Lymphocytosis
- Monocytosis
- Eosinophilia
- Basophilia
Describe the characteristics of leukopaenia
- Neutropaenia
- Lymphopaenia
- Monocytopaenia
- Eosinopaenia
What are the potential causes of altered WBC number and morphology?
- Infection
- Inflammation and endocrine
- Lymphoid and myeloid neoplasia
What does neutropaenia indicate in horses and cattle and why?
Inflammation - neutrophil count dependent on what is being taken out, less produced than taken out indicates inflammation
List the potential causes of neutrophilia
- Inflammation
- Immune mediated anaemia
- Necrosis
- Steroid
- Physiological (stress)
- Chronic neutrophil leukaemia
- Paraneoplastic
- Others e.g. LAD
Explain how steroids lead to neutrophilia
- Stress, steroid therapy, HAC
- Increase release of marrow storage pool cells
- Increase demargination of neutrophils by reducing stickiness to the wall so increase circulating pool
- Prevent extravasation by reducing the stickness
What characteristics indicate that a neutrophilia is due to steroids?
Hypersegmented cells seen in blood due to aging of cells in circulating pool i.e. right shift
Give examples of paraneoplastic causes of neutrophilia
- Rectal polyp
- renal tubular carcinoma
- Metastatic fibrosarcoma
Explain how LAD leads to neutrophilia
- Leukocyte adhesion deficiency
- Will not stick to vessel walls due to lack of adhesion molecules
- Stay in circulation
What may cause increased release of the marrow storage pool of neutrophils?
- endotoxaemia
- Acute infection
- Hypoxia
- Glucocorticoids
What may cause expansion of the marrow precursor pool of neutrophils?
- Chronic infection of inflammation
- Tumours
- Rebound from neutropaenia
- Myeloproliferative disorders
Describe what is meant by a stress leukogram
Low lymphocyte, high neutrophil
List the causes of neutropaenia
- Inflammation (peracute/overwhelming bacterial infections, canine and feline parvo)
- Decreased production: infections, toxicity, neoplasia (leukaemia, myelodysplastic, metastasis), marrow necrosis, myelofibrosis
- Rarely: Immune mediated neutropaenia, Chediak Higashi, acyclic haematopoiesis in grey collies, canine hereditary neutropaenia
In a case of neutropaenia, what is the most likely cause if there is no anaemia, platelets are adequate, and a left shift is present?
Acute inflammation
In a case of neutropaenia, what is the most likely cause if there is no anaemia, platelets are adequate, and a left shift is not present?
- Acute viral infection
- Acute marrow injury
In a case of neutropaenia, what is the most likely cause if there is any combination of: non-regenerative anaemia, thrombocytopaenia, presence of neoplastic cells?
Chronic marrow injury
How should neutropaenia in acute inflammation in the dog or cat be interpreted?
Very severe lesion
How should neutropaenia in acute inflammation in the horse be interpreted?
Probably severe lesion
How should neutropaenia in acute inflammation in the cow be interpreted?
Neutropaenia typical in inflammation regardless of severity
Describe the marrow reserve, regenerative capacity, typical reference interval, typical inflammatory values and uncommon neutrophil counts in dogs
- Reserve: relatively high
- Regen: rapid
- Typical: 3.0-11x10^3/ul
- Inflammation: 12-30x10^3/ul
- Uncommon: >60x10^3uk
Describe the marrow reserve, regenerative capacity, typical reference interval, typical inflammatory values and uncommon neutrophil counts in cats
- Reserve: intermediate
- Regen: intermediate
- Typical: 2.0-12.5x10^3/ul
- Inflammation: 13-25x10^3/il
- Uncommon: >40x10^3/ul
Describe the marrow reserve, regenerative capacity, typical reference interval, typical inflammatory values and uncommon neutrophil counts in horses
- Reserve: intermediate
- Regen: intermediate
- Typical: 2.2-8.6x10^3/ul
- Inflammation: 9-20 x10^3/ul
- Uncommon: >30x10^3/ul
Describe the marrow reserve, regenerative capacity, typical reference interval, typical inflammatory values and uncommon neutrophil counts in cattle
- Reserve: relatively low
- Regen: slow
- Typical: 0.6-4x10^3/ul
- Inflamm: 4-10x10^3/ul
- Uncommon: >20x10^3/ul
Describe the appearance of reactive lymphocytes
- Increased cytoplasmic basophilia
- Perinuclear halo
- Prominent golgi zone (clear are)
- Larger, eccentric, cleavednucleus
- More medium and large vs. peripheral blood small lymphocytes
What are the potential causes of lymphocytosis?
- Catecholamine mediated via splenic contraction (physiological)
- Chronic inflammation
- Young animals and recent vacciantion
- Lymphoproliferative disorder e.g. FeLV, BLV,
- Hypoadrenocorticism
What are the potential causes of lymphopaenia?
- Stress/steroid
- Acute inflammation
- Loss of lymph
- Cytotoxic drugs, radiation
- Immunodeficiency syndrome
- Lymphoma (LN pathology an disrupted circulation)
How does stress/steroid lead to lymphopaenia?
- Endogenous/exogenous, incl stress of being unwell
- Shifts lymphocytes of of circulation and lymphocytolysis
Explain how loss of lymph can lead to lymphopaenia
Chylothorax or lymphangiectasia, meaning circulation is not getting back to the blood
Explain how cytotoxic drugs or radiation may lead to lymphopaenia
Damage to production of lymphocytes/disruption of the circulation
What may cause monocytosis?
- Inflammation: infectious, necrosis, haemolysis, haemorrhage, neoplasia, infarction, trauma
- Steroid/stress
- Monocytic.myelomonocyti c leukaemia
What is the importance of monocytopaenia?
None - no level of monocytes below which we worry
What are teh potential causes of eosinophilia?
- Hypersensitivity
- Parasitism
- Hypoadrenocorticism
- Paraneoplastic
- Idiopathic eosinophilic syndromes
- Eosinophilic leukaemia (v rare)
Give examples of idiopathic eosinophilic syndromes
- Canine eosinophilic bronchopneumopathy
- Myositis
- Feline eosinophilic granuloma
What may cause eosinopaenia?
Glucocorticoids, stress, inflammation
Compare the sensitivity to glucocorticoids of eosinophils and lymphocytes
Eosinophils more sensitive
List potential cuases for the presence of nucleated red cells
- Regenerative anaemias
- Lead toxicity
- EMH and splenic contraction
- Damaged marrow
- Inappropriately high numbers: erythroleukaemia (e.g. erythemic myelosis in cats)
Describe the characteristics of a regenerative left shift
- Segmented > immature
- Neutrophil count increased
Describe the characteristics of a degenerative left shift
- Immature > segmented
- Neutrophil count the same, decreased or increased
- Indicates inability/difficulty to keep up with demand
What may cause neutrophil toxic change?
- Usually severe bacterial infection
- Parvo
- IMHA
- ARF
- DIC
- Neoplasia
What does neutrophil toxic change indicate?
High neutrophil demand
Describe the potential appearance of neutrophil toxic change
- Foamy cytoplasm: dispersed organells (not discrete)
- Diffuse cytoplasmic basophilia
- Doehle bodies: focal blue-grey cytoplasmic structure (RER, RNA)
- Asynchronous nuclear maturation: finely granular nuclear chromatin but in segments
What are toxic changes in neutrophils?
Morphologic abnormalities acquired during maturation under conditions that intensely stimulate neutrophil production and shorted the maturation time in the marrow
What do most toxic neutrophil changes occur as a result of?
Asynchronous maturation between nucleus and cytoplasm
Describe the normal process of granulocytopoiesis
- Lengthening and pinching of nucleus are coordinated with progressive condensation of chromatin and loss of cytoplasmic basiphilia
- Produces white cytoplasm with pink granules, long and fairly narrow nuclei and tightly condensed chromatin
Describe the different appearances of cytoplasmic basophilia in neutrophil toxic change
- Focal: pale blue spots = Doehle bodies (aggregated ribosomes and whorls of RER)
- Streaked
- Diffuse:
What causes the frothy/vacuolated cytoplasm seen in neutrophilic toxic change?
Degranulation of lysosomes
List examples of neutrophil inclusions
- Bacterial: Ehrlichia, Anaplasma
- Viral: canine distemper
- Protozoa: toxoplasma, hepatozoon
- Fungi: histoplasma
- Hereditary/metabolic: Chediak-Higashi, Birman cat anomaly, mucopolysidosis
What are heterophils?
Functional equivalent to neutrophils in which the granules stain red. Found in rabbits, reptiles, birds
Outline the use of WBC differential % and WBC absolutes
- % only for calculation of absolutes
- Absolutes should be used for comparison against reference intervals for clinical purposes
Describe the leukogram pattern associated with excitement
- Mature neutrophilia )2x dogs, horses and cows, >2x in cats)
- Lymphocytosis esp. cats
Describe the leukogram pattern associated with steroid/stress
- Mature neutrophilia
- Lymphopaenia
- Eosinopaenia
- +/- monocytosis
How can total leukocyte count be measured manually?
Haemocytometer
What are the different techniques for the machine measurement of total leukocyte count?
- Impedance
- Laser
- Combined laser and impedance
- Multichannel laser
Which machine technique is best for the counting and sizing of leukocytes?
Impedance - measures change in voltage across receptor to give count and size (degree of change)
Which machine technique is best for the differentiation of leukocytes?
Laser (assess intracellular complexity and lobularity)
List the main disadvantages of automated leukograms
- Non count bands, other WBC precursors or nRBCs
- None report toxic change
- None report WBC inclusions
- None specifically report atypical or reactive morphology
- Bands and metamyelocytes may be miscounted as monocytes
Which is the most reliable method for automated leukograms?
Impedance
Describe the typical acute inflammatory leukogram pattern
- Total WBCs increased
- Segmented neutrophils increased
- Non-segmented neutrophils increased
- Lymphocytes decreased
- Monocyte normal to increased
- Eosinophils low to normal
Describe the typical chronic inflammatory leukogram pattern
- Total WBCs increased
- Segmented neutrophils increased
- Non-segmented neutrophils normal to increased
- Lymphocytes normal to increased
- Monocyte normal to increased
- Eosinophils normal
Describe the typical steroid leukocytosis leukogram pattern
- Total WBCs increased
- Segmented neutrophils increased
- Non-segmented neutrophils normal to slight increase
- Lymphocytes low
- Monocyte increased
- Eosinophils low
Describe the typical physiologic leukocytosis leukogram pattern
- Total WBCs increased
- Segmented neutrophils increased
- Non-segmented neutrophils normal
- Lymphocytes increased
- Monocyte normal to increased
- Eosinophils normal
Describe the typical acute overwhelming inflammatory leukogram pattern
- Total WBCs low
- Segmented neutrophils low
- Non-segmented neutrophils normal to increased
- Lymphocytes low
- Monocyte normal
- Eosinophils low to normal
Describe the typical acute inflammatory with endotoxaemia leukogram pattern
- Total WBCs low
- Segmented neutrophils low
- Non-segmented neutrophils normal to increased
- Lymphocytes low
- Monocyte normal
- Eosinophils low to normal
Describe the typical granulocytic hypoplasia leukogram pattern
- Total WBCs low
- Segmented neutrophils low
- Non-segmented neutrophils normal
- Lymphocytes normal
- Monocyte normal
- Eosinophils normal
Describe the typical ineffective neotropoiesis leukogram pattern
- Total WBCs low
- Segmented neutrophils low
- Non-segmented neutrophils normal
- Lymphocytes normal
- Monocyte normal to increased
- Eosinophils normal
Describe the typical hypoadrenocorticism leukogram pattern
- Total WBCs normal
- Segmented neutrophils low o normal
- Non-segmented neutrophils normal
- Lymphocytes normal to increased
- Monocyte normal
- Eosinophils normal to increased
Describe the typical haemic neoplasia leukogram pattern
- Total WBCs hugely increased
- Cell line affected expected to be increased, other cell lines typically normal or decreased
