Clinical Pathology- Haematology: Leucocytes and Polycythaemia Flashcards
How do leucocytes get transported?
Where are they produced?
What causes their stimulation?
Use blood as transport system
Produced/release from bone marrow and egress into peripheral tissues
Stimulated by cytokines
Which 2 leucocytes are involved in innate immunity and phagocytosis of pathogens?
Which leucocytes are part of adaptive immunity?
Which two leucocytes deffend against parasites?
Neutrophil and monocytes- innate immunity
Lymphocyte- adaptive
Eosinophil/basophil- defense against parasites
Which leucocytes are granulocytes (polylobed nuclei and granules)?
Neutrophil
Eosinophil
Basophil
Fill in the covered names of these leucocytes
What it a leukogram?
Analysis of leucocytes a differential count is absolutely required
No substitute for a smeal exmaination
How many WBC need to be in a single field for leukopenia and leukocytosis?
<15 WBC in a single LPFx10 field- leukopenia
>45 WBC in a single LPFx10 field- leuckocytosis
How can mature and band neutrophils be distinguished?
Mature- nucleus divided into 3-5 lobes- cytoplasm clea or pale pink
Band- u-shaped nucleus, parallel sides, minimal indentation which are not >50% of width of nucleus
What is the role of neutrophils?
Vital role in defence against pathogens-
kill or inactivate bacteria, yeats, fungi or parasites
eliminate infected or transformed cells
modulate the immune response
Involved in regulation of haemopoiesis
What are the different neutrophil pools and where are they found?
Bone marrow:
Proliferative pool
Maturation pool
Storage pool
Blood pools
Some in tissues
Describe neutrophil kinetics
Production regulated by cytokines and growth factors
Maturation time in bone marrow is 7 days
Many neutrophils are stored in BM
Average blood transit time 6-10 hours
On exit from circulation, neutrophils are lost across mucosal surfaces or are removed by macrophages in liver/spleen
If haemopoiesis stops what will be the first manifestation in the blood?
Neutropenia
What is a left shift of neutrophils?
What causes it?
A shift/increase in band immature neutrophils
Caused by a strong inflammatory stimulus- release of more immature forms
What is the difference in regeneratvie and degenerative left shift of neutrophils?
Regenerative- neutrophilia with bands
Degenerative- normal or low mature neutrophil count, increased immature cells, poor prognostic indicator
What can cause neutrophilia?
Physiolgical response- emotional stress/fear, adrenalin
Acute inflammatory response- infection, IMD, neoplasia, necrosis
Stress/corticosteroid induced
Others- uncommon
What is physiological neutrophilia?
Redistribution of mature neutrophils from the marginating pool to the circulating pool:
increased blood flow
stress/fear
May also produce lymphocytosis in cats- can be quite marked, mat also see hyperglycaemia
How can stress/steroid induced neutrophilia be identified?
Mature neutrophilia
release of cells from the storage pool
Shift of cells for marginating to circulating pool
reduced endothelial adherance
What shows up in a stress leukogram?
Neutrophilia
Lymphopenia
Eosinopenia
What changes about a leucogram with an acute inflammatory response?
Neutrophilia with or without a left shift
What happens to leucocytes with toxic change?
Why?
Increases cytoplasmic basophilia (blue colour)
Blue granules (Dohle bodies)
Vacuoles (foamy appearence)
Less condensed chromatin
Due to reduced maturation time in bone marrow because of intense stimulation of myelopoiesis
True or false bacterial infection is the commonest cause of neutrophilia?
False
What can cause neutrophil dysfunction?
Immunodeficiency syndromes
Diabetes mellitis
Neoplasia
FeLV
What causes neutropenia?
Overwhelming demand/decreased survival
Reduced or ineffective granulopoiesis
Rare diseases
What overwhelming demand can cause neutropenia?
Severe bacterial infection:
especially gram negatives
Pyometra
Peritonitis
Pyothorax
What can cause reduced haemopoiesis?
Bone marrow hypoplasia causes pancytopenia- deficiency of RBCs, WBCs and platlets
After chemotherapy drug administration
Parvovirus infection
Idiosyncratic drug reaction
Oestrogens
Chronic ehrlichiosis
Bone marrow infiltration in neoplasia
What do eosinophils do?
Kill parasites
Control hypersensitivity reactions
Effector cells in allergic disease and inflammations
What can cause eosinophilia?
Pasasitic- ecto and endo
Allergic- feline astma, catine atopy, food hypersensitivity
Inflammatory- eosinophilic enteritis, IBD, eosinophilic
Neoplastic- mast cell tumours, occasional lymphoma
Hyperadrenoccotricism
Hypereosinophilic syndrome
What do basophils do?
Potentiate inflammatory/hypersensitivty reactions
IgE and antigen causes degranulation
Histamine release- hypersensitivity reaction
Response in line with eosinophils
What are monocytes?
Circulating precursor of the macrophage
Circulate for short time before migrating into tissues as macrophages
Phagocytose- dead/infected cells, mycobacteria, fungi
Secrete various inflammatory immunomodulatory factors
What causes monocytosis?
Often reflects chronic inflammation
Acute inflammatory response
Tissue necrosis
Immune mediated disease
Compensatory in neutropenia
Part of stress leukogram
What is suggestive of acute inflammation in a leukogram?
Neutropenia and left shift
Where do T/B cells migrate to and from?
T cells from bone marrow to thymus
B cells mature in bone marrow
Second most common leucocyte- most common in cows
What is the B lymphocte function?
Following antigenic stimulation it casuses plasma cells to release Ig
What is the role of T lymphocytes?
Following antigenic stimulation
T helper cells
Cytocxic t cells
T-regulatory cells
What can cause lymphocytosis?
Physiological- adrenalin induced splenic contraction
Prolonged immune stimulation
Youth
Lymphoproliferative disease
Transient post vaccination
Hypoadrenocorticism
What causes lymphopenia?
Corticosteroids
Viral disease- acute phase of viral infections
Loss of lymphocte rich lymph
Sepsis/endotoxaemia
Lymphoma
Can fill in this table?
What is haemopoietic neoplasia?
Leukaemia
What are the different types of leukaemias and how are they different?
Lymphoid lukaeamia- colonal expansion of neoplasit lymphoid
Myeloid leukaemia- neoplastic leukocytes and precursors
Acute- atypical immature cells
Chronic- well differentiated cells
What is polycytaemia/erythrocytosis?
Increase in
PCV/Htc
or
RBC count
or
Hb
What is the difference between relative and absolute polyctaemia?
Relative: proportional changes of RBC numbers in relation to plasma
Absolute: true increase in RBC bumbers due to erythropoiesis
What are some reasons for normal increase in RBCs or HCT?
Normal- some breeds have higher PCV
Splenic contraction- especially in horses
Artefactual
What can cause relative polycytaemia?
- Decreased plasma volume due to fluid shift or dehydration
- Dehyration
- Acute GI disease
- Severe hyperthermia
- RBC redistribution
- Splenic contraction
- Exitement
How is relatvie polycytaemia treated?
Correct fluid and electrolye imbalences
Treat the cause
What is the difference between primary absolute polycytaemia and secondary absolute polycytaemia?
Secondary- due to increased EPO- appropriate/inappropriate
Primary- not due to increases EPO- chronic RBC leukaemia
What is an appropriate secondary absolute polycytaemia?
Can you name some examples?
Response to generalised hypoxia and hypoxaemia
Severe heart disease- congenital right-left shunts, severe lung disease
High altitude
Alveolar hypoventilation
What are innapropriate secondary absolute polycytaemias?
Innapropriate increase in EPO
Renal tumours or other lesions causing localised renal hypoxia
Non renal tumours producing EPO
What can cause a primary absolute polycytaemia?
Well-differentiated myeloprolierative disorder:
mutation in JAK2 gene
How is absolute polycytaemia treated?
remove the underlying cause if possible
stabilise with phlebotomy
