immunology

Question 1

function of C3a, C3b, C5a and C5b

Answer 1

C3a and C5a - mediators of inflammation and phagocyte recruitment
C3b - opsonization and removal of immune complexes
C5b - formation of MAC, lysis

Question 2

what is type 2 hypersensitivity

Answer 2

IgM and IgG mediated immune response against cell bound or cell associated antigens

Question 3

what is type 3 hypersensitivty

Answer 3

IgM and IgG mediated immune complex deposition (they cant be cleared efficiently and get stuck in things where they cause damage

Question 4

two outcomes of Type 2 hypersensitivity

Answer 4

• injury due to activation of effector mechanisms (C’, recruitment of inflammatory cells, activation via Fc R)
• abnormal physiological response by either binding to receptors or proteins interfering with function or by activation/inhibtion

Question 5

unwanted immune mediated response against foreign ABO blood group antigens is an example of

Answer 5

type 2 hypersenstivity responses

Question 6

why do some people produce antibodies against some drugs

Answer 6

because the drug becomes bound to RBCs or platelets which are then the target of anti-drug antibodies

Question 7

type 2 hypersenstivity involving RBCs leads to

Answer 7

haemolytic anaemia or thrombocytopaenia

Question 8

what is haemolytic disease of the newbord

Answer 8

Pregnant mother is Rh positive and foetus is negative. Some RBCs of the foetus will enter the mothers circulation –> mother produces anti-Rh antibodies. With second pregnancy, if foetus if Rh positive –> maternal antibodies will cross the placenta and lyse RBCs of the foetus –> anaemia of the foetus

Question 9

how do you prevent haemolytic disease of the newborn

Answer 9

give mum injection of specific Rh antibody during delivery so that if any foetal RBCs enter maternal circulation, an immune response will be made against them so the mother cant make Ab against Rh

Question 10

what causes goodpastures syndrome

Answer 10

antibodies are made against a variant of collagen type 4 (major component of BM) -> specifically in the kidneys –> complement and phagocyte activation leading to glomerular disease

Question 11

what are the examples of Type 2 hypersensitivity leading to stimulating and inhibitory Ab

Answer 11

stimulatory - graves disease

inhibitory - Myaesthenia gravis

Question 12

what causes graves disease

Answer 12

Abs bind to TSH R on thyroid cells –> stimulates the thymus to produce thyroid hormones –> hyperthyroidism

Question 13

what causes myaesthenia gravis

Answer 13

Ab block the ability of ACh to bind to the R on muscles and therefore no contraction –> atrophy and wasting

Question 14

when does hype 3 hypersensitivity occur

Answer 14

when complexes are excessively produced and inefficiently cleared

Question 15

how are immune complexes normally cleared

Answer 15

by the spleens resident macrophages

Question 16

what are some reasons that immune complexes can be inefficiently cleared

Answer 16

Ag excess
low affinity Ab
inefficient C’ activation

Question 17

how do the immune complexes trigger damage

Answer 17

initiate C’ activation –> C3a and C5a inflammatory activation

Question 18

common outcomes of Type 3 hypersensitivity

Answer 18

vasculitis
glomerulonephritis
arthritis

Question 19

what causes farmers lung

Answer 19

actinomyces in mouldy hay inhaled –> stimulates production of IgG –> alveolitis

Question 20

what is diagnostic of SLE

Answer 20

anti-DNA autoantibodies and immune complex deposition in the kidney

Question 21

what are the 2 forms of immunological tolerance

Answer 21

central tolerance

peripheral tolerace

Question 22

where and what is central tolerance

Answer 22

occurs during development in primary lymphoid organs.

removes self-reactive lymphocytes during development

Question 23

where and what is peripheral tolerance

Answer 23

occurs in the periphery

controls self reactive lymphocytes