Unit 5-6 Flashcards
(29 cards)
what occurs in a hyperacute rejection?
involves AB and complement: recipient has Ab due to previous exposure (previous graft) or ABO mismatch causing an immediate Ab binding and complement cascade. This leads to vasospasm via anphylatoxins and histamine
what T cells (and associated cytokines) recognize:
HLA-A
HLA-B
HLA-D
A and B- weakly recognized by CTLs–> but if Th1 derived IL-2 nearby, CTL become cytotoxic
D- recognized by Th1, which secretes IL-2 to help activate CTL, and secretes IFNgamma which is proinflammatory and activates M1
HLA-DR is linked with
RA
SLE
Goodpasture’s Syndrome
DMT1
what are “M1”
- macrophages (activated by IFNgamma) that avidly ingest bacteria and foreign bodies
- secrete their own cytokines (TFNalpha and IL-1), which intensify inflammation
Distinguish Class I and Class II histocompatibility antigens
MHC I- HLA-A, HLA-B
- on all nucleated cells
- CTL
MHC II- HLA-D
- on macrophages, DC, B cells, and Langerhan cells
- Th cells
what do Tregs secrete and what are those things functions?
secrete TGFbeta and IL-10
-very potent at suppressing/down-regulating Th and Th2
what codes for MHC II in HLA
HLA-DR
*first noticed by Th1 cells
mediators that communicate between (mostly) leukocytes
interleukins
what determines what a T cell will differentiate into?
the experience of the DC APC prior (what PRPs were engaged, what cytokines or chemokines predominated)
discuss how T cells selected to recognize ‘self + X’ also recognize foreign MHC (allorecognition).
Th cells normally see MHC II + peptide; also detect foreign MHC II
CTL normally detect MHC I + peptide; also detects foreign MHC I
**recognition of foreign MHC is a chance for cross-rxn bc receptors are selected to recognize self-MHC + antigen during maturation in thymus
how to CTL become activated
- DC present antigen to them in lymph node
- also require help from Th1 in the form of IL-2
what is the function of CTLs
identify infected self-cells and signal them for apoptosis
MHC gene set that you inherit from one parent
Haplotype
why is HLA-27 associated w/ ankylsoing spondylitis
- there is cross reactivity between klebsiella bacteria and B27–> leading to autoimmunity
- HLA-B27 is also prone to misfolding which could cause inflammation
what are “M2”
-macrophages (activated by IL-4) that help with healing (debris removal, scar formation, walling off pathogens M1 failed to kill)
what do Th2 secrete and what are that things functions?
-IL-4–> chemotactic for (and activates) macrophages (M2) and eosinophils
what MHC class do macrophages and DC have
MHC I and MHC II
what are the main functions of Tfh
- help B cells that have recognized antigen become activated and mature/differentiate into antibody secreting plasma cells
- Direct B cells to switch from IgM secreting to IgG, IgA, or IgE
what are the 3 main types of HLA-D gene loci
DR** most important for transplant
DP
DQ
__ recognize the HLA-D loci of foreign MHC Class II receptors. They are stimulated to release IFNγ to attract more macrophages and also IL-2 to help CTL cells function.
Th1 cells
What cells are HLA-A, HLA-B, and HLA-D found on?
HLA-A and HLA-B: all nucleated cells– MHC I-CD8 and thus linked to CTL cells
HLA-D: Macrophages, DC, B cells, Langerhan cells–MHC II-CD4 and thus linked to Th1, Th2, Treg and create MLR
what would occur w/o Treg cells
autoimmunity/ over reactive immune response
Tfh often direct B cells to switch IgM secretion to what in these locations?
gut
spleen
Gut: IgA
Spleen: IgG
what is a MLR
occur when leukocytes from the donor are mixed with leukocytes from the recipient to identify immune response.
