Immunity Flashcards
CD28
T cell coreceptor
Binds B7 on APCS
CD40L
T cell coreceptor
Binds CD40 on APCs
After receiving Signal 1 + Signal 2, T cells release
IL-12 -> amplification
Signal 1 for B cell activation
Antigen endocytosis -> MHC II expression -> TCR binding
Signal 2 for B cell activation
Costimulation Binding (CD40 cross linking)
Light Chain Immunoglobulin
One constant
One variable domain (kappa or lambda)
Heavy Chain Immunoglobulin
One variable
Three (IgG/A/D) or Four (IgE/M) Constant domains
Distinguished by alpha/delta/epsilon/gamma/mew
Most variable region & why
CDR3 - due to VDJ junctional diversity and somatic hypermutation during affinity maturation (Activation induced Deaminase (AID) -> cytosine replaced by uracil)
Initial immunoglobin types formed
IgM and IgD - generated by alternate splicing
FCgRI
High affinity for IgG, found on mø and nø
Phagocytosis
FCgRIIa
Low affinity for IgG
mø and nø
Phagocytosis
FCgRIIb
Low affinity
Bø
Antibody regulation
FCgRIIIa
Low affinity
NK, mø
ADCC -> granule & perforin release
FCgRIIIb
Low affinity
nø
Phagocytosis
MHC Class I
HLA A, B, C alleles
8-9 aa peptide
Expresses endogenous proteins via proteosome, TAP1 & 2.
MHC Class II
HLA DP, DQ, DR
13-25aa peptide -> open ended
Binds exogenous peptides via endosomes and ER. Invariant chain acts as chaperone.
Hypersensitivity Type I
Acute
IgE/Mast cell mediated
Anaphylotoxins (complement, etc)
eg. Pollen/nut allergies
Hypersensitivity Type II
Antibody mediated
eg. Haemolytic disease of the newborn/blood transfusions
Hypersensitivity Type III
Immune Complex Mediated
eg. Glomeronephritis (streptococcus), Lyme disease, lupus
Hypersensitivity Type IV
Delayed type
T cell mediated
eg. contact dermatitis, tuberculosis
