Lecture 16 - Immune activation, helper cells and regulation

Question 1

Generalisation of class I and II fucntions?

Answer 1

class II presents phagocytosed antigen, class I presents peptide fragments of invaded antigen

Question 2

Class II receptors?

Answer 2

exogenous pathway, found on B cells and specialised APCs, presents peptides to CD4 T cells

Question 3

Class I receptors?

Answer 3

endogenous pathway, found on virtually all nucleated cells, present ‘non-self’ peptides to CD8 cells thats odd from ‘self-peptides’

Question 4

MHC difference in peptide grooves?

Answer 4

greater amount of peptide presented in class II and a lot more beta surrounding - class I contains beta2 microglobulin

Question 5

Adhesion molecules?

Answer 5

selectins (weak interactions, velcro-like) and integrins (strong cell-cell adhesion, hold cells in tissue together, hold lymphocytes together for activation

Question 6

Weak adhesion - selectins?

Answer 6

low affinity, rapid association and dissociation: L-selectin, P-selectin (platelets, stick endothelial cells to neutrophils), E-selectin (vascular endothelium, induced by inflammatory cytokines, bond to leukocytes)

Question 7

Adhesion molecule process?

Answer 7

neutrophil has weak binding interactions w vessel wall through selectins, this triggers increased integrin expression, slowing down the neutrophil to a halt, strong binding triggers migration

Question 8

Lymphocyte activation - step 1?

Answer 8

integrin/IgSF interaction adhering lymphocyte to antigen presenting cell

Question 9

Lymphocyte activation - step 2?

Answer 9

T cell receptor attempts to match with MHC receptor, if not then detaches, if so interacts with antigen presenting cell w aid from co-stimulators/checkpoint regulators

Question 10

Checkpoint regulators/co-stimulator pairs?

Answer 10

B7 on APC CD28 on T Cell; CD40 on B cell CD40L; upregulated when APC is infected or B cell detects antigen w surface Ig, when no affected lack of signal 2 sends T cell away (dont forget about co-inhibitors)

Question 11

Cytokine properties?

Answer 11

pleiotropic (act on many cell types e.g. IL-4), redundant (many types fulfil same purpose), synergistic (work together for desired affect e.g. amplification), antagonistic