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
nonrecirculating memory T cells that are found in epithelial barrier tissues, including the GI tract, lung, skin, and reproductive tract.
TISSUE RESIDENT MEMORY T CELLS (TRM)
TRM markers
TRM marker** CD69**
surface marker CD103
Langerhans cells are characterized by their high expression of of what CD
CD1a and unique expression of langerin (CD207)
this s required for Birbeck granule formation
langerin (CD207)
M1 or M2?
These macrophages have the ability to phagocytize large numbers of pathogens and kill intracellular bacteria
M1
for efficient intracellular killing macrophages, vitamin D is required for the adaptive immune responses to overcome the ability of intracellular pathogens to avoid this killing
These macrophages are thought to play a central role in response to parasites, tissue remodeling, and allergic diseases, and may have a role in resolution of skin inflammation
M2
mast cell receptor for IgE
FCεRI
Mast cells express the receptor for immunoglobulin E (FCεRI) constitutively on their surface, and the bestknown cause of mast cell activation is when antigens crosslink immunoglobulin E bound to these receptors.
Mast cell receptor for IgG
FcγRII
most abundant leukocytes in the blood accounting for about 35% to 70% of the peripheral blood leukocytes
Neutrophils
life span of neutrophils
5 to 90 hours
They are the hallmark cell of acute inflammation secondary to their high mobility and are usually recruited to sites of injury within minutes.
Neutrophils
Eosinophils are readily recruited into tissues in response to appropriate stimuli such as?
interleukin-5 (IL-5) and the eotaxin chemokines CCL11 (eotaxin-1), CCL13, and CCL26 (eotaxin-3)
cytokines that promote eosinophilia by inducing IL-5 production
The epithelial cell–derived cytokines thymic stromal lymphopoietin (TSLP), a common cytokine in atopic dermatitis, IL-25 (IL-17E), and IL-33 all promote eosinophilia by inducing IL-5 production.
Whare do mast cells mature?
tissues
Where do basophils mature?
bone marrow
defined by the presence of basophilic granules in the cytoplasm, by the surface expression of the highaffinity Fc receptor for immunoglobulin E (FceRI) and by the release of chemical mediators such as histamine, after stimulation
Basophils
most abundant cell type in skin and form the epidermis
Keratinocytes
