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Activation of T cells without co-stimulation may lead to the unresponsiveness of the T cell (also called anergy), apoptosis or the acquisition of the immune tolerance. [ 3 ] The counterpart of the co-stimulatory signal is a (co-)inhibitory signal, where inhibitory molecules interact with different signaling pathways in order to arrest T cell ...
B cell activation: from immature B cell to plasma cell or memory B cell Basic B cell function: bind to an antigen, receive help from a cognate helper T cell, and differentiate into a plasma cell that secretes large numbers of antibodies. B cell activation occurs in the secondary lymphoid organs (SLOs), such as the spleen and lymph nodes. [1]
The entire mechanism ensures that an activated T cell only stimulates a B cell that recognizes the antigen containing the same epitope as recognized by the T cell receptor of the "costimulating" T helper cell. The B cell gets stimulated, apart from the direct costimulation, by certain growth factors, viz., interleukins 2, 4, 5, and 6 in a ...
ITAMs are important for signal transduction, mainly in immune cells. They are found in the cytoplasmic tails of non-catalytic tyrosine-phosphorylated receptors [7] such as the CD3 and ζ-chains of the T cell receptor complex, the CD79-alpha and -beta chains of the B cell receptor complex, and certain Fc receptors.
Priming is the first contact that antigen-specific T helper cell precursors have with an antigen. It is essential to the T helper cells' subsequent interaction with B cells to produce antibodies. [1] Priming of antigen-specific naive lymphocytes occurs when antigen is presented to them in immunogenic form (capable of inducing an immune response).
Central tolerance is essential to proper immune cell functioning because it helps ensure that mature B cells and T cells do not recognize self-antigens as foreign microbes. [2] More specifically, central tolerance is necessary because T cell receptors (TCRs) and B cell receptors (BCRs) are made by cells through random somatic rearrangement. [1]
The process of formation begins when the T-cell receptor binds to the peptide:MHC complex on the antigen-presenting cell and initiates signaling activation through formation of microclusters/lipid rafts. Specific signaling pathways lead to polarization of the T-cell by orienting its centrosome toward the site of the immunological synapse. The ...
Helper T cells recognize these by expressing the CD4 co-receptor. The activation of a resting helper T cell causes it to release cytokines and other signals (green arrows) that stimulate the activity of macrophages, killer T cells, and B cells, the last of which produces antibodies. The proliferation of Helper T cells stimulates B cells and ...