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

The Major Histocompatibility Complex class II (MHC II)-T cell receptor (TCR) complex is the central molecular interaction governing the initiation of the adaptive immune response. MHC II molecules, expressed on professional antigen-presenting cells such as dendritic cells and B cells, present exogenous peptide fragments to the TCR on CD4+ T helper cells [1]. This interaction is stabilized by the CD4 co-receptor, which binds to the non-polymorphic region of the MHC II molecule, facilitating the recruitment of signaling molecules like Lck to the TCR complex [2]. Activation of this complex triggers a signaling cascade that leads to T cell proliferation, cytokine secretion, and the coordination of both cellular and humoral immunity [3]. Dysregulation of the MHC II-TCR interaction is implicated in numerous autoimmune conditions, such as rheumatoid arthritis and multiple sclerosis, where self-antigens are incorrectly recognized as foreign [4]. Therapeutic strategies targeting this complex include MHC II competitors like glatiramer acetate, CD4-directed antibodies like ibalizumab, and TCR modulators like teplizumab, all aimed at either suppressing pathological immune responses or enhancing protective immunity [5]. Sources: [1] Roche & Furuta (2015) Nat Rev Immunol; [2] Gaud et al. (2018) Nat Rev Immunol; [3] StatPearls (2023) MHC Class II; [4] Jones et al. (2006) Nat Rev Immunol; [5] Schooten et al. (2018) J Immunol Res.

Other names

MHC II-peptide-TCR complexHLA-TCR interactionCD4-MHC II-peptide complexAntigen-MHC-TCR complexCD4+ T cell activation complex

Inhibition of antigen presentation or blockade of T cell receptor signaling to modulate adaptive immune responses.