What is the function of T follicular helper cells?
T follicular helper cells (Tfh) are a specialized subset of CD4+ T cells that were first identified in the human tonsil. They play a critical role in protective immunity helping B cells produce antibody against foreign pathogens.
How are T follicular helper cells activated?
A subset of naive T cells in the T cell zone are activated by antigen and migrate to the follicles where they differentiate into TFH cells that interact with and instruct Follicular B (Fo B) cells to undergo isotype switching, somatic hypermutation, and rapid cellular division to seed germinal centers (GC).
What do Tfh cells produce?
Tfh cells produce IL-21 and promote immunoglobulin class switching and affinity maturation. Tfh cells are characterized by high expression of the surface markers programmed cell death protein 1 (PD-1), inducible co-stimulator (ICOS), and the chemokine receptor CXCR5 for targeting to B-cell zones.
Where are Tfh found?
Tfh cells are found in secondary lymphoid tissues, including tonsils, spleen, and lymph nodes. The role of Tfh cells is to trigger germinal center (GC) B cells into antibody-secreting plasma and memory B cells [2,3].
What is T regulatory cells?
Regulatory T cells (Tregs) are a specialized subpopulation of T cells that act to suppress immune response, thereby maintaining homeostasis and self-tolerance. It has been shown that Tregs are able to inhibit T cell proliferation and cytokine production and play a critical role in preventing autoimmunity.
What are follicular B cells?
Follicular B cells populate the B cell follicles of the spleen and lymph nodes, associating with follicular dendritic cells. They have a mature B cell phenotype that is distinct from other B cell populations, recirculate in the blood and require cognate help from T cells to become antibody-producing memory B cells.
What does T helper cells activate?
Helper T cells are arguably the most important cells in adaptive immunity, as they are required for almost all adaptive immune responses. They not only help activate B cells to secrete antibodies and macrophages to destroy ingested microbes, but they also help activate cytotoxic T cells to kill infected target cells.
What is follicular dendritic cells?
Follicular dendritic cells (FDCs) are stromal cells residing in primary follicles and in germinal centers of secondary and tertiary lymphoid organs (SLOs and TLOs). There, they play a crucial role in B-cell activation and affinity maturation of antibodies.
What is TFH cell?
T follicular helper (Tfh) cells are a specialized subset of CD4+ T cells that collaborate with B cells to promote and regulate humoral responses. Unlike other CD4+ effector lineages, Tfh cells require interactions with both dendritic cells (DCs) and B cells to complete their differentiation.
Do follicular helper T cells promote immunoglobulin class switching?
Function of Tfh cells in normal immune responses In addition to IL-21, Tfh cells secrete cytokines associated with other CD4+ T-effector cell subsets, including IL-4 and IFNγ (66–69), enabling differential Ig class switching.
What do regulatory T cells secrete?
Types. Regulatory T cells are a subset of T cells that can secrete tolerogenic cytokines such as IL-10 and suppress the proinflammatory functions of effector T cells such as their cytotoxicity, cytokine production, and proliferation.
What is the major function of T regulatory cells quizlet?
Regulatory T cells secrete anti-inflammatory cytokines to regulate immune function.
What is the role of T follicular helper cells in antigens?
Ab responses against most antigens (Ags) require interactions between B cells and CD4 (+) T helper cells, and it is now well recognized that T follicular helper cells (Tfh) specialize in providing cognate help to B cells and are fundamentally required for the generation of T cell-dependent B cell responses.
Which receptor controls Follicular Regulatory T cells in the blood?
The receptor PD-1 controls follicular regulatory T cells in the lymph nodes and blood. Nat Immunol. 2013;14:152–161. [PMC free article][PubMed] [Google Scholar] Schmitt N, Ueno H. Blood Tfh Cells Come with Colors. Immunity. 2013;39:629–630. [PMC free article][PubMed] [Google Scholar]
What is the role of ICOs in the development of follicular T cells?
The costimulatory molecule ICOS regulates the expression of c-Maf and IL-21 in the development of follicular T helper cells and TH-17 cells. Nat Immunol.
What is the pathophysiology of interferon-γ excess in follicular T cells?
Interferon-γ excess leads to pathogenic accumulation of follicular helper T cells and germinal centers. Immunity. 2012;37:880–892.