RT Book, Section A1 Lucas, Fabienne A1 Gribben, John A2 Kaushansky, Kenneth A2 Prchal, Josef T. A2 Burns, Linda J. A2 Lichtman, Marshall A. A2 Levi, Marcel A2 Linch, David C. SR Print(0) ID 1178757663 T1 Functions of T Lymphocytes: T-Cell Receptors for Antigen T2 Williams Hematology, 10e YR 2021 FD 2021 PB McGraw-Hill Education PP New York, NY SN 9781260464122 LK hemonc.mhmedical.com/content.aspx?aid=1178757663 RD 2024/03/29 AB SUMMARYAll T cells express an antigen receptor formed by two polymorphic polypeptides that are invariably associated with the CD3 complex containing CD3γ, CD3δ, CD3ε, and ζ subunits, as well as multiple accessory molecules. These proteins are necessary for surface expression and signaling by the T-cell receptor (TCR). On most T cells, the TCR is formed by α and β polypeptides. In a small T-cell subset, receptors are formed by γ and δ polypeptides. The diversity of these TCR polypeptides is comparable to that estimated for immunoglobulin (Ig) molecules. However, unlike Igs, TCR antigen recognition requires antigen presentation by defined major histocompatibility complex molecules on the plasma membrane of another cell, the antigen-presenting cell (APC). T-cell response to antigen depends on the intensity of the signal generated by ligation of the TCR and is modified by the simultaneous ligation of other accessory molecules. Interactions at the contact sites between T cells and APCs are organized in the immunologic synapse. The outcome of T-cell antigen recognition can range from immune activation and T-cell proliferation to specific T-cell tolerance or programmed cell death.