1-POM-2-2: White blood cells

Question 1

What is the origin of white blood cells ?

Answer 1

multipotent haemopoietic stem cells give rise to a myeloblast which the gives rise to granulocytes and monocytes

Question 2

what do Granulocytes refer to?

Answer 2

1. neutrophils
   2.Basophils
   3.eosinophils
   ( these all have granules present in the cytoplasm that contain agents essential for their microbial function)

Question 3

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

Answer 3

signalling through myeloid growth factors

Question 4

Where does normal granulocyte maturation take place?

Answer 4

bone marrow

Question 5

How long does a neutrophil granulocyte survive?

Answer 5

7-10 hours in circulation before migrating to tissues

Question 6

What is the key physical characteristic of neutrophils?

Answer 6

nucleus of mature neutrophil is segmented (lobulated)

Question 7

What is the main function of a neutrophil ?

Answer 7

defence against infection, it phagocytes and the kills micro-organism (bacteria), they also phagocytose cell debris helping recycle the tissues which are being broken down

Question 8

What is the main function of eosinophils ?

Answer 8

defence against parasitic infections

they are also important in the regulation of type 1 hypersensitivity reactions ( they inactivate the histamine and leukotrienes released by basophils and mast cells)

Question 9

What do the basophil granules contain?

Answer 9

stores of histamine
, heparin and proteolytic enzymes

Question 10

what immune and inflammatory responses are Basophils involved in ?

Answer 10

• Mediation of the immediate-type hypersensitivity reaction in which IgE-coated basophils release histamine and leukotrienes
• Modulation of inflammatory responses by releasing heparin and proteases
• Mast cells are similar to basophils, but reside in tissues rather than the circulation

Question 11

What are the key roles that Monocytes play ?

Answer 11

1. phagocytosis of micro-organisms covered with antibody and complement
2. Phagocytosis of bacteria/fungi
3. antigen presentation to lymphoid and other immune cells

Question 12

where do B lymphocytes originate form

Answer 12

in foetal liver and bone marrow

Question 13

Where do lymphoid progenitors migrate from to, that leads to the development of T lymphocytes?

Answer 13

T cell development is initiated when immature progenitor cells migrate from the fetal liver or adult bone marrow to the thymus

Question 14

What abnormalities can occur with white blood cells ?

Answer 14

1. Transient leucocytosis= suggests a reactive cause and occurs when a healthy bone marrow responds to an external stimuli such as infection, inflammation or infraction (death of tissue resulting from a failure of blood supply)
2. Persistent leucocytosis= suggests a primary blood cell disorder- the leucocyte count is abnormal due to acquired somatic DNA damaged affecting a haematopoietic precursor cell giving rise to blood cancers such as leukaemia, lymphoma, myeloma

Question 15

what is leucocytosis?

Answer 15

to many white blood cells

Question 16

what is leukopenia

Answer 16

a reduction in total number of white cells

Question 17

neutropenia?

Answer 17

reduction in neutrophil count

Question 18

lymphopenia ?

Answer 18

reduction in lymphocyte count

Question 19

what is the most abundant leukocyte in the circulation

Answer 19

neutrophil hence it is more likely that leukocytosis/leukopenia is due to changes in the neutrophil count

Question 20

what are some causes of neutrophilia ( too many neutrophils)

Answer 20

-infection, inflammation, infraction, other tissue damage
-may also occur during pregnancy, or after exercise, after administration of corticosteroids

Question 21

why may exercise cause neutrophilia?

Answer 21

exercise causes rapid shift of neutrophils from the marginated pool to the circulating pool

Question 22

what is myeloproliferative disorder (primary blood cancer) associated with ?

Answer 22

neutrophilia, basophilia and left shift

Question 23

What is an examples of myeloproliferative disorders?

Answer 23

Chronic myeloid/ granulocyte leukaemia (CML)

Question 24

what is neutrophilia accompanied by?

Answer 24

toxic changes and left shift

Question 25

What is left shift ?

Answer 25

an increase in non-segmented neutrophils or that there are neutrophil precursors in the blood ( immature neutrophils)

Question 26

When can neutropenia occur ?

Answer 26

• after chemotherapy, radiotherapy
• autoimmune disorders
• severe bacterial infections
• certain viral infections and drugs
• due to ethnicity

Question 27

what are patients with very low neutropenia at risk for

Answer 27

they are at high risk of serious infections and at a higher risk of dyeing form sepsis
- they need urgent intravenous antibiotics

Question 28

How many lobes should a normal neutrophil have

Answer 28

between 3 and 5 segments/lobes

Question 29

What does Neutrophil hyper-segmentation mean ?

Answer 29

an increase in the average number of neutrophil lobes/segments (right shift)

Question 30

when does right shift normally occur

Answer 30

due to a lack of vitamin B12 or folic acid

Question 31

When do you normally see Eosinophilia

Answer 31

• allergy
• parasitic infection
• asthma
• eczema
• drugs
• some forms of leukaemia eg CML

Question 32

When does basophilia take place

Answer 32

• leukaemia especially CML

Question 33

when does Monocytosis (too many monocytes) take place ?

Answer 33

infection, chromic inflammation, some types of leukaemia

Question 34

What are the causes of lymphocytosis

Answer 34

viral infection (transient)
lymphoproliferative disorder e.g chronic lymphocytic leukaemia

Question 35

What are the causes of lymphopenia

Answer 35

• HIV infection
• Chemotherapy
• Radiotherapy
• Corticosteroids

Question 36

What is leukaemia?

Answer 36

• cancer of the white blood cells
• they can either be myeloid or lymphoid depending on if the mutation in the bone marrow is in a myeloid or lymphoid progenitor
• leukaemic cells replace normal haempoietic cells in the bone marrow