Immunology Flashcards
Six Types of T Cells
Th1 Th2 Th17 Tfh Treg CTL
Th1 Cells
Binds APCs in periphary, release INF-gamma for macrophage chemotaxis and maturation to M1s and IL-2 for CTl activation
Th17
Release IL-17 for macropahge chemotaxis and M1 maturation, greater effect that Th1s
Th2
Bind APCs, release IL-4 for macropahge chemotaxis and maturation into M2 repair macrophages. Activate eosinophils
Tfh
follicular helpers, activate B cells in lymph node cortex and promote class switching
Treg
Release TGF-beta and IL-10 to reduce/stop immune response by preventing T cell activation
CTL
killer T cell, recognize MHC I, not cytokine dependent, cause apoptosis in infected cells
All T Cell Surface Marker
CD3
B Cell Surface Markers
CD20 and ABs
Helper T Cell Surface Markers
CD3 and CD4
CTL Surface Markers
CD3 and CD8
Cytokine
short range mediator that affects cell behavior of same or other cell
Lymphokine
Cytokine released by lymphocyte
Chemokine
Small, short range mediators that cause inflammation
Follicular Helper details
Either Th1 or Th2 lineage but w/ additional marker CXCR5. Th1 promote complement ABs (IgG) and Th2 promote IgE.
Also regional attributes: IgA promoting in GI tract
Mitogen
Molecule that triggers mitosis
B Cell vs. T Cell Receptors
B Cell: AB w/ 3 CDRs, 2 heavy and 2 light chains, bind epitopes or opsonize
T Cell: 2/3 CDRs recognize MHC, 1/3 recognize peptides, made of 1 alpha and 1 beta chains, not secreted.
Dendritic Cells Cross-Presentation
Extrinsic pathway in DCs place AG on both MHC II for T helper activation and MHC I for CTL activation
T-Independent AGs
Molecules w/ same epitope repeated many times (ex carbohydrates), activate B cells w/o T cell help, only IgM is produced
Basics of Thymus Maturation
Thymocytes divide, rearrange TCRs and express both CD4 and CD8. Interact w/ thymus endothelial cells that show only self protein. If 2/3 CDR binding to MHC give survival signal, 3/3 CDR binding causes apoptosis (some become Tregs), 0/3 CDR binding causes apoptosis.
HLA-A; HLA-B; and HLA-DR
Most important loci in the Human Leukocyte Antigen gene complex for MHC specificity.
HLA-A and B make MHC I
HLA-DR makes MHC II
Class I and II MHC antigen structures
MHC I has 1 variable chain and invariable beta-2-microglobulin chain
MHC II has 2 variable alpha and beta chains
30 minor AGs
Alloantigen
Antigen present in some people that will react w/ an Allo-Antibody in another person
Haplotype
set of alleles/SNPs that are inherited together
Which alleles are most important to match in transplants?
MHC II matches (HLA-DR) are most important since it activates helpers to release IFN-G to attract macrophages and IL-2 to make CTls more toxic.
W/o helper activation, CTLs do little damage.
One-Way Mixed Leukocyte Reaction
Testing for tissue rejection.
WBCs from both donor and recipient. Donor WBC kills lymphocytes but retains monocytes. Add both together, if recipient lymphocytes react to donor MHC, there will be lymphocyte proliferation.
Hyperacute Rejection
Recipient has IgG or IgM to donor HLA or blood type. ABs bind endothelial cells of graft and activated complement. Vasospasm occurs and graft may never get perfused.
Alloreaction to foreign MHC
Recognition of foreign MHC is a chance cross-reaction. T cells are programmed to recognize self MHC + some peptide but not self MHC w/o peptide. However, foreign MHC w/o peptide binds self TCRs just differently enough from self MHC that it “feels” like there is self + peptide there.
This explains why T cell immunity is not transfusable between individuals because TCRs will not bind sufficienctly to foreign MHC with peptide to cause activation.
Ankylosing Spondylitis
Inflammation of tendon insertions or fibrous joints that produce calcification.
Associated w/ HLA-B27 allele, pathology is uncertain but might involve inability to recognize a pathogen, autoimmunity, or accumulation of misfolded protein.
HLA-DR3 and 4
Associated w/ juvenile diabetes
Local Immunity
MALT in GI tract produces and secretes IgA which binds pathogens in lumen before invasion
Cell-Mediated immunity most effective for…..
viruses, intracellular bacteria
Anti-serum
ABs isolated from human or animal that are used to opsonize toxin (ex. tetanus, rattle snake venom)
Toxoid
an inactivated toxin that promotes AB production against the active toxin
Conjugate Vaccine
Used for T-independent antigens. Give antigen w/ attached second AG that promotes T cell response (thus class switching) when it is expressed on MHC after intrinsic pathway
Herd Immunity
Vaccination rate reduces chance that unvaccinated run into infected individuals.
Level necessary for herd protection is based on virulence of specific virus (must be really high w/ measles)
