Lecture 23 Flashcards
(15 cards)
What are examples of innate lymphocytes?
MAIT, iNKT, Vδ1, Vδ2, NK
What are some properties of unconventional “innate” T cells?
non-MHC restricted, conserved throughout species, invariant/semi-invariant TCR, enriched in tissues in humans and mice
Are innate T cells rare? Where are they found?
Not rare, 12-20% of T cells, tissue resident
How do unconventional and MHC-restricted T cell response times relate?
Unconventional happens earlier and ends sooner
What is the major function of innate T cells? How does their localization help this?
stress surveillance –> detect changes and maintain homeostasis, metabolically adapted to be tissue resident
What are iNKT cells? What are their properties?
invariant natural killer T cells
Invariant TCR (mVα14-Jα18-Vβ7/8 or hVα24-Jα18-Vβ11), recognize lipids, restricted by CD1d, highly conserved
What is the antigen to iNKT cells?
α-Galactosylceramide (aGalCer) = microbial lipids
How do iNKT cells compare with adaptive T cells?
subsets have similarities, develop in thymus with CD1d and self lipid presented by thymocyte to TCR, then move to tissues, also transactivate other immune cells (APC, T, NK, B)
How do iNKT cells act in health and disease?
activate macrophages through IFNγ and TNFα
direct killing through release of perforin, granzyme upon presentation of lipid by CD1
What antigens do γδ T cell receptors recognize?
exogenous and autoantigens
self or non-self proteins, lipids and/or phosphorylated isoprenoids
Why are γδ T cells fast responders?
“pre-programmed,” mature in thymus and do not require further maturation in the periphery or clonal expansion
What are the γδ T cell subsets? What are they characterized by?
Rorγt PLZF (Th17-like): no/weak TCR engagement, produces IL-23R, IL-1 R I, γδ TCR, TNF, IL-17
Tbet (Th1-like): TCR engagement, produces IL-18R, IL-12R, NKR, CD27, IFNγ, γδ TCR, perforin granzyme, cytotoxicity
How do γδ T cells develop?
through thymic waves
self-renewing/persisting Tγδ17 cells are in peripheral tissues
continuous export of naive γδ T cells after birth
What are the major functions of γδ T cells?
lysis of stressed/infected cells, cytokine and chemokine production, B cell help and IgE production, priming of αβ T cells via antigen presentation, dendritic cell maturation, regulation of stromal cell function via growth factor production
What are MAIT cells? What are their features and where are they found?
mucosal associated invariant T cells
bacterial metabolite sensing, innate cytokine responsiveness, tissue/inflammation homing receptors
enriched at barriers
