linking adaptive and innate L6

Question 1

MHCs

Answer 1

TWO TYPES MHC1 MHC2, these are important for activating T/B cells to let know that these are pathogens to respond to

naive cells - never seen Ag before

Question 2

MHC1

Answer 2

present intracellular antigens like viral proteins

found on all nucleated cells as all cells can be infected, lets immune system know its infected

recognised by CTL CD8+ receptors

triggers killing of infected cells

Question 3

MHC2

Answer 3

presents extracellular antigens like bacterial antigens
only found on APCs - macrophage, B and DC, as need phagocytosis for this

recognised by Treg/Th CD4+ receptors

coordinate immune responses, secretes IFN-Y etc.

Question 4

MHC are diverse

Answer 4

need a wide range to present a wide range of antigens, the more diverse the better

MHC alleles are codominant so halo-type is set of MHC cells on each chromosome
MHC define accepting or rejection of grafts as foreign MHC molecules in graft may activate recipient T cells which kills graft, so need to match holotype

these are highly polymorphic

Question 5

To fully activate T cells requires 2 signals

Answer 5

signal 1- MHC-Ag with TCR

signal 2 - co stimulation due to DAMPS causing upregulation of B7, which binds to CD28 on T cells to say this microbe is from a pathogen and need to activate to respond

without this, no activation and T cell dies or deactivates, this ensures that if presenting self-antigen, no response

Question 6

macrophages APC

Answer 6

activates Th cells to then produce IFN-Y which increase macrophage activation

Question 7

B cell as APC

Answer 7

need permission from previous activated Th, ones already activated by DC in order to activate

Question 8

DC as APC

Answer 8

sample, traveller and presented

Question 9

T-dependent Ab respond

Answer 9

B cells when acting as APC do so, so they can be activated, but can only do this with a previously activated Th cell.

This Th cell binds to the same antigen it did on the DC/MACRO so knowns its a pathogen

this allows full effector functions of B cell, switching isotopes and affinity maturation and long lasting respond

Question 10

t-indepdent Ab response

Answer 10

B cell can activate without this but limited effector functions, no isotope switching so remains IgM, normally stimulated by PAMPs

Question 11

activation of immune memory cells

Answer 11

much easier to activate and can be activated by more APC types, not just DC

Question 12

resolving immune response

Answer 12

As infection clears, less DAMPS/PAMPS, less antigens, less presentation and less activating, less B7 signals

Treg cells develop and IL-10 cytokines for inhibitory effects to control and stop response