Flashcards in 8. Antigen Processing and Presentation II (Snippets) Deck (50)
what are the three signals to activate naive lymphocytes to specific effector?
1. antigen receptor (TCR-peptide/MHC)
2. costimulation (CD28/B7)
3. Cytokines (lead to specific effector functions)
central dovma of adaptive immunity?
Phenotypic changes to the DC = 'loss of DC adhesiveness" and means that the chemokine receptors change when the DC becomes stimulated and moves out of the epithelium. They become lymp node-attracted at this point, which is based on the changes to the type of chemokine receptors expressed. Important for stimulation of both CD4 and CD8 cells
phenotypic changes to the DC:
- increase class II and class I
- upregulate B7
- change chemokine receptors
- go from a phagocytic phenotype to a processing machine
Th1 cells do what?
macrophage activation: destruction of phagocytosed microbe
Th-all, esp TFH cells do what? (T-follicular helper)
B cell antibody secretion: antibody binding to microbe
CD8 cells do what?
kill antigen-expressing infected cells
dendritic cells do what?
macrophages do what?
APCs when activated by T cells or PAMPA; otherwise they clean things up
B cells do what?
present BCR-binding antigens to antigen-specific T cells
when do DCs express Class II MHC?
constitutive, but increases as mature
when do macrophages express Class II MHC?
low; induced by IFN-gamma
when do B cells express Class II MHC?
constitutively, augmented by cytokines
costimulation (eg B7) is inducible how in DCs?
by PAMPS, pro-inflamm cytokines, and CD40-40L
costimulation (eg B7) is inducible how in macrophages?
by PAMPs, proinflamm cytokines, CD40-40L
costimulation (eg B7) is inducible how in B cells?
by T cells (CD40-40L) and antigen
what is the principle function of DCs?
initiation of naive T cell responses to protein (CD4 and CD8)
what is the principle function of macrophages?
induction and effector phases of CMI
what is the principle function of B cells?
present antigen to antigen-specific CD4 helpers
naive and some memory T cells require cosimulation (eg B7) - what about effector T cells?
do not require costimulation, only the ag/MHC recognition
part of the innate immune system making large amounts of Type I IFNs upon activation (hopefully can take care of pathogen without adaptive immunity)
TCR recognizes the peptide/MHC complex
T cells respond vigorously to APC bearing non-self MHC alleles, in the so called _____ response (the bane of transplantation surgeons)
Class I and Class II genes are very polymorphic - each allele will bind what?
a particular set of peptides, which in turn will activate different clones of antigen-specific T cells
what part of the Class I MHC is MHC encoded?
only H chain
peptides that bind class I MHCs are generated where?
Class I molecs are upregulated during infection via what?
cytokines, exp gamma IFN
class II molecs are expressed by which cells?
B cells, DCs, macrophages, and thymic epithelium
peptides that bind class II MHC are generated where?
Class II MHC are upregulated during infection via what?
cytokines, esp gamma IFN
Treg cells do what?
dampen immune response