White blood cells

Question 1

What do granulocytes and monocytes differentiated from?

Answer 1

myeloblasts, which are differentiated from common myeloid progenitors

Question 2

What are the 3 granulocytes?

Answer 2

Eosinophils, neutrophils, basophils

Question 3

What differentiates from a monocyte?

Answer 3

Macrophages

Question 4

Where are the granules in granulocytes contained and what do they contain?

Answer 4

granules present in the cytoplasm that contain agents essential for their microbicidal function

Question 5

What is essential for the proliferation and survival of myeloid cells?

Answer 5

Signalling through myeloid growth factors such as as G-CSF, M-CSF, GM-CSF

Question 6

How long does a neutrophil granulocyte survive in the circulation before migrating to tissues?

Answer 6

7-10 hrs

Question 7

What does the nucleus of the mature neutrophil look like?

Answer 7

Segmented

Question 8

What is the main function of a neutrophil and how does it carry out this function?

Answer 8

Its main function is defence against infection; it phagocytoses and then kills micro-organisms

Question 9

Explain the process of neutrophil migration into tissues and phagocytosis

Answer 9

The first step in neutrophil migration to tissues is chemotaxis

Neutrophils become marginated in the vessel lumen, adhere to the endothelium and migrate into tissues

Phagocytosis of micro-organisms occurs following cytokine priming

Question 10

Do eosinophils spend more or less time in circulation than neutrophils?

Answer 10

Less time

Question 11

What is the main function of eosinophils?

Answer 11

Its main function is defence against parasitic infection

Question 12

Explain the role of eosinophils in hypersensitivity.

Answer 12

Eosinophils are important in the regulation of Type I (immediate) hypersensitivity reactions: inactivate the histamine and leukotrienes released by basophils and mast cells

Question 13

What is contained in the granules of basophils?

Answer 13

Its granules contains stores of histamine and heparin, as well as proteolytic enzymes

Question 14

How long do monocytes spend in the circulation?

Answer 14

Several days

Question 15

What are the 3 roles of monocytes?

Answer 15

phagocytosis of micro-organisms covered with antibody and complement
phagocytosis of bacteria/fungi (cf antibody)
antigen presentation to lymphoid and other immune cells

Question 16

What do macrophages store and release?

Answer 16

Iron

Question 17

What do macrophages develop from and where?

Answer 17

Monocytes migrate to tissues where they develop into macrophages and other specialised cells that have a phagocytic and scavenging function

Question 18

What is the intravascular lifespan of lymphocytes?

Answer 18

Very variable

Question 19

Where do B lymphocytes originate?

Answer 19

Fetal liver and bone marrow

Question 20

What does development of B lymphocytes involve and what does it lead to?

Answer 20

Ig heavy & light chain gene rearrangement
This leads to production of surface Igs against many different antigens

Question 21

What does subsequent maturation of B cells require?

Answer 21

exposure to antigens in lymphoid tissue e.g lymph nodes

Question 22

When does transient leukocytosis occur?

Answer 22

occurs when a normal or healthy bone marrow responds to an external stimulus such as infection, inflammation or infarction

Question 23

What is the cause of neutrophilia or monocytosis?

Answer 23

Bacterial infection, or inflammation

Question 24

What is the cause of lymphocytosis?

Answer 24

Viral infection

Question 25

What is the cause of eosinophilia?

Answer 25

Parasitic infection or allergy

Question 26

What is the cause of basophilia?

Answer 26

usually leukaemia

Question 27

What is the cause of persistent leukocytosis

Answer 27

Primary blood cell disorder- The leukocyte count is abnormal due to acquired somatic DNA damage affecting a haematopoietic precursor cell giving rise to blood cancers such as leukaemia

Question 28

What is leukopenia?

Answer 28

Reduction in total number of white cells

Question 29

When is neutrophilia normal?

Answer 29

During pregnancy or after exercise (caused by a rapid shift of neutrophils from the marginated pool to the circulating pool) and after administration of corticosteroids

Question 30

What is toxic granulation?

Answer 30

heavy coarse granulation of neutrophils

Question 31

What can neutrophilia be accompanied by?

Answer 31

toxic changes and ‘left shift’

Question 32

What is left shift?

Answer 32

Left shift means that there is an increase in non-segmented neutrophils (band forms) or that there are neutrophil precursors in the blood

Question 33

When can neutropenia have a physiological basis?

Answer 33

benign ethnic neutropenia in people of African or Afro-Caribbean ancestry

Question 34

How many segments should a neutrophil have and what is it called when it has too many?

Answer 34

3-5. it is called hypersegmentation

Question 35

What is the cause of hypersegmentation?

Answer 35

lack of vitamin B12 or folic acid (megaloblastic anaemia)

Question 36

What are the causes of lymphopenia?

Answer 36

HIV infection Chemotherapy Radiotherapy Corticosteroids

Question 37

What does leukaemia result from?

Answer 37

Results from a number of somatic mutations in oncogenes or tumour-suppressor genes occurring in a primitive cell that, as a result, has a growth or survival advantage over normal cells. Functionally useless leukaemic clones steadily replace normal cells

Question 38

What does leukopenia usually result from and why?

Answer 38

low neutrophil count since this is usually the most abundant leuckocyte in the circulation