Immunology Exam 2 Flashcards
(35 cards)
IL-7 importance
IL-7 important for T and B cell maturation/differentiatin/development
what are 3 mechanisms for antibody diversity
- rearrangement
- junctional diversity
- somatic hypermutation (B cells only)
describe T cell positive selection
where does it occur
after beta 1st and alpha 2nd chain rearrangement, T cells undergo positive selection
- signal = T cell moves on
- no signal = alpha chain rearrangement occurs
after alpha chain rearrangement, positive selection occurs again
- signal = T cell moves on
- no signal = cell dies
thymic cortex
describe T cell negative selection
where does it occur
after positive selection, T cells travel to the medulla for negative selection
strength of TCR & MHC/antigen
- just right = T cells leave the thymus
- too strong = death
- too weak CD8 death and CD4 transitions into T regulatory cell, iNKT or MAIT
thymic medulla
what is MHC critical for
T cell activation
what is B7 and CD28 critical for
what does CTLA4 do
T cell survival (2nd signal)
binds to B7 with higher affinity than CD28 shut down T cell
what are IL6, IL12, IL23, IL4 critical for
T cell differentiation
what is IL2 critical for
clonal expansion into helper T cells and cytotoxic T cells
clonal expansion/proliferation for B cells
what are the proinflammatory cytokines for T helper cell I
IL1, IL6, TNF alpha (released by injured cells)
*IFN gamma (activated macrophages)
IL8 (neutrophil recruitment)
CD40
Fas (apoptosis)
IL-3 (extracellular bacteria)
IL2 (proliferation)
what are the antiparasitic/allergy cytokines for T helper cell 2
*IL4 (isotype switch to IgG or IgE)
*IL5 (eosinophil recruitment)
IL13 (allergies)
what are the regulatory/antiinflammatory cytokines for T regulatory cells
*TGF beta (regulates T cell homeostasis & inhibits TCR autoreactivity)
*IL10 (suppress NK cells & APC from proinflammatory cytokine release)
IL-35
what cytokines are important for T cell/B cell maturation/proliferation
IL2 (proliferation of T cells) secreted by T cells (autocrine/paracrine)
IL7 (maturation of T and B cells) secreted by stromal cells in the thymus
what are the proinflammatory cytokines for T17 helper cells
IL17 A & F
IL-22
CD40
IL3
TNF alpha
cytokines for Tfh cell
IL-21
what is CCL21
chemokine by lymph node to attract dendritic cells
what is CCL19
chemokine by dendritic cells to attract T cell to lymph node
what effector molecules and proinflammatory cytokines are part of cytotoxic T cells
perforin, granzymes, Fas ligand
IFN gamma
TNF beta
TNF alpha
what forms the conjugate pair of B cells and T cells
B cells CD40 + T cells CD40L
B cells ICAM1 + T cells LFA-1
what cytokines are released from T cells onto B cells
IL2,4,5
describe B cell somatic hypermutation
B cell undergoes somatic hypermutation to try and increase the affinity for the antigen
mediated by activation-induced cytidine deaminase (AID)
variable regions are altered
affinity tested on follicular dendritic cells
mutations with increased affinity selected for isotype switch
mutation with decreased affinity = apoptosis
describe B cell isotype switch
the constant region is changed
mediated by activation-induced cytidine deaminase (AID)
required CD40/CD40L for expression of B7 for release of cytokines
IgM –> IgG, IgA, or IgE
how and why are removal of antibody complexes important
RBC have CR2 which bind C3b which is bound to antibodies
Macrophages remove RBC bound to antibodies + C3b in spleen/liver
Amyloidosis will occur if not removed = organ dysfunction
IgM
pentamer (bulky)
high avidity, low affinity
complement activation = opsonization/phagocytosis, inflammation and MAC
first antibody to be produced
IgA
monomer (B cells) = opsonization/phagocytosis
dimer (mucosal surfaces) = neutralization
maternal antibodies via colostrum
high affinity
FcaR1 on phagocytic cells
predominant on mucosal surfaces
