White Blood Cells Flashcards
Define leukocytosis
Increase in white cell count
Define neutrophilia
Increase in neutrophil count
Define lymphocytosis
increase in lymphocyte count
Define monocytosis
Increase in monocyte count
Define eosinophilia
Increase in eosinophil count
Define basophilia
Increase in basophil count
Define leukopenia
Decrease in white blood cells
Define neutropenia
decrease in neutrophils
Define lymphopenia
decrease in lymphocytes
Define monocytopenia
Decrease in monocytes
Define eosinopenia
decrease in eosinophils
How do white blood cells leave blood vessels in an immune response?
marginal pool of WBCs on the outskirts of the capillary lumen so they can get out if needed
What can be a trigger for a shift from the maginal to circulating pool?
- Epinephrine
- Glucocorticoids
- Infection
- Stress
What is the proportion of WBCs in the circulating pool of the cat?
25-50%
What is the proportion of WBCs in the circulating pool of the dog?
50%
What is the proportion of WBCs in the marginal pool of the cat?
50-75%
What is the proportion of WBCs in the marginal pool of the dog?
50%
What does the neutrophil count in blood depend on?
Balance between neutrophils going out of the blood to fight infection vs the speed at which they are being replaced by the bone marrow
What are possible causes of neutrophilia?
Inflammation
Infections (bacterial, viral, fungal, protozoal)
Immune mediated anaemia
Necrosis (including haemolysis, sterile inflammation and FB’s)
(Inflammatory mediators must be able to get from lesion to circulation to reach marrow – think about superficial skin, LUTD, CNS)
Steroid
Stress
Steroid therapy
Hyperadrenocorticism
Physiological
Epinephrine
Fight or flight (excitement, fear, pain, exercise)
Chronic neutrophil leukaemia
Paraneoplastic
(rectal polyp, renal tubular carcinoma, metastatic fibrosarcoma)
Other
E.g. LAD
How does the location of neutrophils change during different situations?
What does a left shift in neutrophils?
Presence of immature cells
What is a regenerative left shift?
- segmented (mature) > immature
- increased neutrophils
What is a degenerative left shift?
- immature > segmented
- decreased neutrophil count
What are possible causes of left shift neutrophilia?
significiant inflammatory demand will pull immature (banded) cells out
What does a right shift in neutrophils mean?
Neutrophils are made to stay in the circulation rather than go off to be recycled - means they are hypersegmenting (how they mature)
What is neutrophil toxic change?
- Rapid neutropoiesis - not going thorugh whole maturation cycle
- Usually severe bacterial infection
- Other example assocations (Parvo, IMHA, ARF, DIC, neoplasia)
- Prognostic indicator
What is the only way to see toxic change?
Through blood smear
How can we recognise toxic change in cytology?
Foamy cytoplasm
Dispersed organelles (not discrete –EDTA)
Diffuse cytoplasmic basophilia
Persistent of cytoplasmic RNA
Incl segmented neutrophils
Döhle bodies
Focal blue-grey cytoplasmic structures (RER/RNA)
Isolated finding in some healthy cats
Asynchronus nuclear maturation
Finely granular nuclear chromatin but in “segments”
Which one of these is the toxic neutrophil?
C - normal band neutrophil
D - toxic band neutrophil
Which one of these is the toxic neutrophil?
A - normal mature neutrophil
B - toxic neutrophil
What are possible neutrophil inclusions?
- Bacterial (Ehrlichia, Anaplasma)
- Viral (Canine distemper)
- Protozoa (Toxoplasma, Hepatozoon)
- Fungi (Histoplasma)
- Hereditary/metabolic (Chediak-Higashi, Birman cat anomaly, mucopolysidosis)
What are heterophils?
Functionally equivalent cell to neutrophils with red coloured granules
In rabbits, reptiles and birds
What are possible neutropenia causes?
- Inflammation
- Decreased production
What can cause decreased production of neutrophils?
- Infections: parvovirus, FeLV, toxoplasma
- Toxicity: chemotherapy, oestrogen, chloramphenicol (cats)
- Neoplasia: leukaemia, myelodysplastic, metastatic
- Marrow necrosis
- Myelofibrosis
How does neutrophil marrow reserve vary by species?
Dog - relatively high
Cat - intermediate
Horse - intermediate
Cow - relatively low
How does the neutrophil regeneration capacity vary by species?
Dog - rapid
Cat - intermediate
Horse - intermediate
Cow - slow
Which cells disapear first in cytopenia? Why?
When there is marrow disruption, lineage kinetics result in disappearance of neutrophils first, then platelets then RBC’s
Because it takes hours for bone marrow to produce neutrophils, days for platelets and months for RBCs.
How is neutrophil circulation different from lymphocyte circulation?
Neutrophils have a one way life from bone marrow to being destroyed
Lymphocytes circulate around the body - for defence memory (long lived)
What are reactive lymphocytes?
- Immunocytes, plasmacytoid lymphocytes
- Stimulated T or B
- Inflammation (esp chronic)
- Young animals
- ↑ cytoplasm
- ↑ cytoplasmic basophilia
- Perinuclear halo
- Prominent Golgi zone
- ↑, eccentric, cleaved nucleus
- More medium and large (i.e., vs peripheral blood “small”)
What are these lymphocytes?
Reactive lymphocytes
What causes lymphocytosis?
Physiological - Catecholamine mediated via splenic contraction (especially cats)
Chronic Inflammation
Chronic antigenic stimulation
May include reactive lymphocytes
Usu with neutrophilia and/or monocytosis (±eosinophilia)
Young animals and recent vaccination
Lymphoproliferative disorder (incl FeLV, BLV)
May be lymphopenia in lymphoma
Hypoadrenocorticism
Loss of normal level of lymphocyte inhibition by glucocorticoids
What causes lymphopenia?
Stress/steroid
Endogenous or exogenous glucocorticoid
shifts lymphocytes out of circulation & lymphocytolysis
**Acute inflammation **
Bacterial, viral or endotoxaemia
Migration to inflamed tissue and homing to LN’s
Often with neutrophilia or neutropenia
Correction of lymphopenia → better prognosis
Loss of lymph - Chylothorax (drainage) or lymphangiectasia
Cytotoxic drugs, radiation
Immunodeficiency syndrome
Lymphoma - LN pathology and disrupted circulation
How are monocytes and macrophages linked?
Monocytes are blood resident
Differentiate into macrophages when they enter tissues
What are these cells?
Monocytes
What does the presence of monocytes trigger?
Results in release of immune mediators (cytokines)
What causes monocytosis?
Inflammation
May imply “chronic”
Bacterial, fungal, protozoal
Necrosis: haemolysis, haemorrhage, neoplasia, infarction, trauma
Inconsistent finding (chronic but also acute inflammation)
Steroid/Stress
Stress
Glucocorticoids (occ ACTH)
Hyperadrenocorticism
Monocytic/myelomonocytic leukaemia
Monocytopenia not recognised a clinically significant entity
What causes eosinophilia?
- Hypersensitivity
- Parasitism
- Hypoadrenocorticism
- Paraneoplastic (esp Mast cell but also others)
- Idiopathic eosinophilic syndromes (E.g., canine eosinophilic bronchopneumopathy, myositis, feline eosinophilic granuloma etc
Eosinophilic leukaemia - v rare)
What causes eosinopenia?
- Glucocorticoids, stress, inflammation
- Many reference intervals include “0”
What are these cells?
Eosinophils
What are these cells?
Basophils
When do we see nucleated red cells?
- Can be present in moderate numbers in regenerative anaemias, lead toxicity
- EMH and splenic contraction, damaged marrow
- Present in inappropriately high numbers in erythroleukaemia (erythemic myelosis; cats)
What are these cells?
Neoplastic undefined cells
What can glucocorticoid stress cause on WBC count?
- Mature neutrophilia (3)
- Lymphopenia (2)
- Eosinopenia (1)
- ± Monocytosis (4)
WHat does catecholamine mediated excitement cause on WBC count?
Triggered during travel, capture, chutes & handling
Mature neutrophilia
Lymphocytosis - esp. cats
Resolves within hours or less
