Clinical Pathology- Haematology: Leucocytes and Polycythaemia

Question 1

How do leucocytes get transported?

Where are they produced?

What causes their stimulation?

Answer 1

Use blood as transport system

Produced/release from bone marrow and egress into peripheral tissues

Stimulated by cytokines

Question 2

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?

Answer 2

Neutrophil and monocytes- innate immunity

Lymphocyte- adaptive

Eosinophil/basophil- defense against parasites

Question 3

Which leucocytes are granulocytes (polylobed nuclei and granules)?

Answer 3

Neutrophil

Eosinophil

Basophil

Question 4

Fill in the covered names of these leucocytes

Answer 4

Question 5

What it a leukogram?

Answer 5

Analysis of leucocytes a differential count is absolutely required

No substitute for a smeal exmaination

Question 6

How many WBC need to be in a single field for leukopenia and leukocytosis?

Answer 6

<15 WBC in a single LPFx10 field- leukopenia

>45 WBC in a single LPFx10 field- leuckocytosis

Question 7

How can mature and band neutrophils be distinguished?

Answer 7

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

Question 8

What is the role of neutrophils?

Answer 8

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

Question 9

What are the different neutrophil pools and where are they found?

Answer 9

Bone marrow:
Proliferative pool
Maturation pool
Storage pool

Blood pools

Some in tissues

Question 10

Describe neutrophil kinetics

Answer 10

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

Question 11

If haemopoiesis stops what will be the first manifestation in the blood?

Answer 11

Neutropenia

Question 12

What is a left shift of neutrophils?

What causes it?

Answer 12

A shift/increase in band immature neutrophils

Caused by a strong inflammatory stimulus- release of more immature forms

Question 13

What is the difference in regeneratvie and degenerative left shift of neutrophils?

Answer 13

Regenerative- neutrophilia with bands

Degenerative- normal or low mature neutrophil count, increased immature cells, poor prognostic indicator

Question 14

What can cause neutrophilia?

Answer 14

Physiolgical response- emotional stress/fear, adrenalin

Acute inflammatory response- infection, IMD, neoplasia, necrosis

Stress/corticosteroid induced

Others- uncommon

Question 15

What is physiological neutrophilia?

Answer 15

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

Question 16

How can stress/steroid induced neutrophilia be identified?

Answer 16

Mature neutrophilia

release of cells from the storage pool
Shift of cells for marginating to circulating pool
reduced endothelial adherance

Question 17

What shows up in a stress leukogram?

Answer 17

Neutrophilia

Lymphopenia

Eosinopenia

Question 18

What changes about a leucogram with an acute inflammatory response?

Answer 18

Neutrophilia with or without a left shift

Question 19

What happens to leucocytes with toxic change?

Why?

Answer 19

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

Question 20

True or false bacterial infection is the commonest cause of neutrophilia?

Answer 20

False

Question 21

What can cause neutrophil dysfunction?

Answer 21

Immunodeficiency syndromes

Diabetes mellitis

Neoplasia

FeLV

Question 22

What causes neutropenia?

Answer 22

Overwhelming demand/decreased survival

Reduced or ineffective granulopoiesis

Rare diseases

Question 23

What overwhelming demand can cause neutropenia?

Answer 23

Severe bacterial infection:

especially gram negatives
Pyometra
Peritonitis
Pyothorax

Question 24

What can cause reduced haemopoiesis?

Answer 24

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

Question 25

What do eosinophils do?

Answer 25

Kill parasites Control hypersensitivity reactions Effector cells in allergic disease and inflammations

Question 26

What can cause eosinophilia?

Answer 26

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

Question 27

What do basophils do?

Answer 27

Potentiate inflammatory/hypersensitivty reactions IgE and antigen causes degranulation Histamine release- hypersensitivity reaction Response in line with eosinophils

Question 28

What are monocytes?

Answer 28

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

Question 29

What causes monocytosis?

Answer 29

Often reflects chronic inflammation Acute inflammatory response Tissue necrosis Immune mediated disease Compensatory in neutropenia Part of stress leukogram

Question 30

What is suggestive of acute inflammation in a leukogram?

Answer 30

Neutropenia and left shift

Question 31

Where do T/B cells migrate to and from?

Answer 31

T cells from bone marrow to thymus B cells mature in bone marrow Second most common leucocyte- most common in cows

Question 32

What is the B lymphocte function?

Answer 32

Following antigenic stimulation it casuses plasma cells to release Ig

Question 33

What is the role of T lymphocytes?

Answer 33

Following antigenic stimulation T helper cells Cytocxic t cells T-regulatory cells

Question 34

What can cause lymphocytosis?

Answer 34

Physiological- adrenalin induced splenic contraction Prolonged immune stimulation Youth Lymphoproliferative disease Transient post vaccination Hypoadrenocorticism

Question 35

What causes lymphopenia?

Answer 35

Corticosteroids Viral disease- acute phase of viral infections Loss of lymphocte rich lymph Sepsis/endotoxaemia Lymphoma

Question 36

Can fill in this table?

Answer 36

Question 37

What is haemopoietic neoplasia?

Answer 37

Leukaemia

Question 38

What are the different types of leukaemias and how are they different?

Answer 38

Lymphoid lukaeamia- colonal expansion of neoplasit lymphoid Myeloid leukaemia- neoplastic leukocytes and precursors Acute- atypical immature cells Chronic- well differentiated cells

Question 39

What is polycytaemia/erythrocytosis?

Answer 39

Increase in PCV/Htc or RBC count or Hb

Question 40

What is the difference between relative and absolute polyctaemia?

Answer 40

Relative: proportional changes of RBC numbers in relation to plasma Absolute: true increase in RBC bumbers due to erythropoiesis

Question 41

What are some reasons for normal increase in RBCs or HCT?

Answer 41

Normal- some breeds have higher PCV Splenic contraction- especially in horses Artefactual

Question 42

What can cause relative polycytaemia?

Answer 42

* Decreased plasma volume due to fluid shift or dehydration * Dehyration * Acute GI disease * Severe hyperthermia * RBC redistribution * Splenic contraction * Exitement

Question 43

How is relatvie polycytaemia treated?

Answer 43

Correct fluid and electrolye imbalences Treat the cause

Question 44

What is the difference between primary absolute polycytaemia and secondary absolute polycytaemia?

Answer 44

Secondary- due to increased EPO- appropriate/inappropriate Primary- not due to increases EPO- chronic RBC leukaemia

Question 45

What is an appropriate secondary absolute polycytaemia? Can you name some examples?

Answer 45

Response to generalised hypoxia and hypoxaemia Severe heart disease- congenital right-left shunts, severe lung disease High altitude Alveolar hypoventilation

Question 46

What are innapropriate secondary absolute polycytaemias?

Answer 46

Innapropriate increase in EPO Renal tumours or other lesions causing localised renal hypoxia Non renal tumours producing EPO

Question 47

What can cause a primary absolute polycytaemia?

Answer 47

Well-differentiated myeloprolierative disorder: mutation in JAK2 gene

Question 48

How is absolute polycytaemia treated?

Answer 48

remove the underlying cause if possible stabilise with phlebotomy