Antibody and T cell receptor (TCR (for T cell receptor); Ig (for immunoglobulin, i.e., antibody))

**Antibodies and T cell receptors (TCRs)** are structurally related immune molecules that enable the adaptive immune system to recognize and respond to a vast array of antigens. T cell receptors are membrane-bound heterodimers (most commonly alpha/beta chains) found on T cells that detect specific antigenic peptides presented by major histocompatibility complex (MHC) molecules, thus initiating T cell activation, proliferation, and effector functions[1][2][3][4][5][6]. TCRs are non-covalently associated with the CD3 complex, which transduces activation signals. Antibodies (immunoglobulins) are secreted or cell-surface immunoglobulin molecules with similar V(D)J-driven antigen recognition domains; unlike TCRs, antibodies can bind soluble antigens without MHC presentation. Both play key roles in immunity, disease pathogenesis, and immunotherapy—TCRs are targeted directly (OKT3, CARs) or indirectly (checkpoint therapy) in immuno-oncology and transplantation, while antibodies constitute the basis for many biotherapeutics (e.g., rituximab, trastuzumab). Because "Antibodies and T cell receptors" is an overly broad term (encompassing two distinct, canonical immune receptor types), it is not a precise designation for a single druggable molecular target, but rather denotes two classes of essential immune receptors[2][5][6].

Other names

TCRT-cell antigen receptorimmunoglobulinantibodyimmunoglobulin receptor

Blockade or depletion of T cells via antibody-mediated cytotoxicity (OKT3, alemtuzumab) Antigen-specific recognition and cytotoxicity (CAR-T, BiTE) Modulation of T cell activation or tolerance via immune checkpoint inhibitors Immunosuppression by interfering with TCR signal transduction