2 - 11 - CELLULAR COMPONENTS OF THE CUTANEOUS IMMUNE SYSTEM Flashcards
primary cells of the adaptive immune system
T and B cells
key players of the innate immune system
dendritic cells and macrophages
provide a rapid first line of defense against microbial pathogens to contain them
Innate immune system
key lineages of T cells
αβ and γδ
T cells that have completed their primary development in the thymus, and have not yet encountered their specific antigen
naïve T cells
- circulate through the bloodstream to secondary lymphoid organs including lymph nodes and the spleen
- Once a naïve T cell meets its specific antigen, presented to it as a peptide MHC complex on the surface of an antigen-presenting cell in secondary lymphoid organs, it is able to develop into an effector T cell and a longerlived central memory T cells
In contrast to naïve T cells, these T cells are able to mount a response to antigens.
effector T cells
Naive CD8 + T cells recognize peptide antigens in the binding pocket of what MHC class molecules?
MHC class I molecules such as HLA-A, HLA-B, or HLA-C,
and differentiate into cytotoxic effector T cells, which recognize and kill infected cells
Naïve CD4 +T cells recognize peptide antigens in the binding pocket of what MHC class molecules?
MHC class II molecules such as HLA-DR, HLA-DQ, and HLA-DP on antigen-presenting cells and differentiate into effector subsets that have broader and different immunologic functions
This includes the main CD4 +T-cell subsets, T helper 1 (TH 1), TH 2, TH 17, and T follicularhelper (TFH), and T regulatory cells (Tregs)
main mediators of cell-mediated immunity
TH1 cells
TH 1 cells are characterized by the production of what cytokines?
IL-2, IFN-γ, and TNF-α
TH 2 cells are characterized by the production of what cytokines?
IL-4, IL-5, and IL-13.
facilitate humoral (antibody) responses and inhibit some cell-mediated immune responses
TH2 cells
TH 17 cells are characterized by the production of what cytokines?
IL-17A, IL-17F, IL-21, IL-22, and recently IL-26
depend on IL-23 for their survival and expansion, and are regulated by the transcription factor RORyt
Th17 cells
Th17 cells depend on what IL for their survival and expansion?
IL-23
involved in antigen responses against extracellular pathogens including both bacteria and fungi
Th17 cells
These cells have been implicated as key players in the pathogenesis of psoriasis.
Th17 cells
play a key role in maintaining tolerance to selfantigens in the periphery
T REGULATORY CELLS (TREGS)
This condition is characterized by loss of Tregs which results in multiorgan autoimmune disease.
IPEX (immune dysregulation, polyendocrinopathy, enteropathy, and X-linked) syndrome
They are characterized by expression of the transcription factor FOXP3, the genetic cause of IPEX syndrome.
represent a distinct subset of CD4 +T cells primarily found in B-cell areas of lymph nodes, spleen, and Payer patches
T FOLLICULAR HELPER CELLS (TFH )
trigger the formation and maintenance of germinal centers in lymph nodes and spleen through the expression of CD40 ligand (CD40L) and the secretion of IL-21 and IL-4
T FOLLICULAR HELPER CELLS (TFH )
These cells play a crucial role in orchestrating selection and survival of B cells that go on to differentiate into either antibody-producing plasma cells or memory B cells
T FOLLICULAR HELPER CELLS (TFH )
T follicular helper T cell produce which cytokines?
IL-21 and IL-4
To gain entry into the skin, T cells need to express what surface molecules and chemokine receptors?
cutaneous lymphocyte antigen (CLA), 9and expression of specific chemokine receptors including CCR4 and CCR10
