Lecture 1

Question 1

what are the four main sources of infection?

Answer 1

bacteria
viruses
fungi
parasites

Question 2

for an effective immune response, the immune system must …. (3)

Answer 2

be able to recognise and respond to any invading organism
not over-react to benign or self
be able to direct different effector mechanisms against different pathogens

Question 3

what are the features of specific/adaptive immunity?

Answer 3

clonal distributed receptors
larger repertoire - low frequency of cells specific for any antigen
response takes time to develop
memory cells produced

Question 4

stages of clonal selection

Answer 4

1. removal of potentially self-reactive immature lymphocytes by clonal deletion (self-antigens)
2. pool of mature naive lymphocytes (foreign antigen)
3. proliferation and differentiation of activated specific lymphocytes to form a clone of effector cells (effecter cells eliminate antigen)

Question 5

how is a BCR expressed by B lymphocytes?

Answer 5

membranes form of Ig binds “free antigen” is subsequently secreted when B cell is activated now known as antibody

Question 6

what is the structure of an antibody?

Answer 6

two identical antigen-binding sites

constant and variable regions

Question 7

what are the 5 antibody classes?

Answer 7

IgM
IgG
IgD
IgE
IgA

Question 8

what comprises an antibody domain?

Answer 8

two beta sheets linked by disulphide bridges

Question 9

features of TCR?

Answer 9

membrane bound
smaller than BCR
heterodimer of alpha and beta chain
4 Ig domains 
each chain contributes 3 CDRs to Ag binding

Question 10

features of MHC class I molecules?

Answer 10

expressed on all nucleated cells 
heterodimer 
HLA-A, HLA-B, HLA-C
alpha1 and alpha2 domains fold to form beta sheet
very polymorphic

Question 11

features of MHC class II molecules?

Answer 11

expression on APCs only
heterodimer
alpha and beta chains encoded by separate genes encoded within the MHC
similar to MHC I structure