Major histocompatibility complex class II – T cell receptor complex (MHCII-TCR complex) (MHCII-TCR complex)

The Major histocompatibility complex class II – T cell receptor (MHCII-TCR) complex is a fundamental molecular assembly of the adaptive immune system, facilitating the recognition of exogenous antigens by CD4+ T helper cells (Janeway et al., 2001). This complex is formed when an antigen-presenting cell (APC) displays a processed peptide on an MHC class II molecule, which is then specifically bound by a cognate T cell receptor (TCR) (StatPearls, 2023). The interaction is stabilized by the CD4 co-receptor, which binds to the non-polymorphic region of the MHCII molecule and recruits the kinase Lck to initiate intracellular signaling cascades (NIH, 2022). Dysregulation of this complex is central to the development of autoimmune diseases, such as multiple sclerosis and rheumatoid arthritis, where self-peptides are erroneously recognized as foreign (PubMed, 2021). Therapeutically, the complex is targeted by immunosuppressants that block downstream signaling or by agents like glatiramer acetate that compete for MHCII binding to induce immune tolerance (PubChem, 2023).

Other names

MHC class II – CD4 T cell receptor complexHLA class II – T cell receptor complexMHCII-peptide-TCR complexAntigen-MHCII-TCR complexCD4-MHCII-TCR complex

Modulation of T cell activation by interfering with the interaction between the MHC class II-peptide complex and the T cell receptor, or by inhibiting downstream signaling pathways (e.g., calcineurin inhibition) and co-stimulatory signals required for the functional assembly of the complex.