essential immunology 3 Flashcards
Difference between active and passive immunity?
active:
- transfer of microbe or microbial antigen to host
- generates memory cells
- response takes a few weeks
- antigens present
Passive:
- transfer to host of antibodies or T-lymphocytes
- no antigens or memory cells
- response is immediate
what are memory cells?
- cells generated after an immune response
- allow second response to be much larger and faster
- memory cells have a much greater affinity to the antigen than naive cells
what are antigens?
how to B-cells and T-cells vary in their response to antigens?
Antigens are any substance capable of generating an immune response.
Epitome: site on antigen which can be recognised my a B-cell receptor
Fc site: site where antigen binds to cell.
B-cells can recognise free-flowing antigens due to the B-cell receptors
T-cell can only recognise antigens when attached to MHC.
Antibody structure?
light chain + heavy chain linked by disulphide bridges.
variable region and constant region.
constant region always the same in immunoglobulins of same class. variable region different between different b-cells
different classes of antibodies?
IgM- can activate the compliment system. good at opsonisation. first antibody activated.
IgG- good at opsonisation- can cross placenta
IgA- good neutraliser, protects mucosal surfaces-can neutralise stomach acid
IgE- involved in allergy response and anaphylactic shock.
IgD-function still unknown
Different types of B-cell activation?
T-cell dependent: B-cell receptor cluster as they bind to antigen. T-cell then sends signal of binding to same antigen
T-cell independent: B-cell cluster together as they bind to antigen with many repeating epitomes-A mitogen.
How is B-cell activation triggered by the compliment system?
C3 converts cleaves into C3a and C3b
c3b cleaves into C3d which binds to B-cell.
while B-cell bound, Igm bind to epitotes. triggers activation
