T-cell receptor recognizing peptide-MHC class II complex (TCR (via MHC class II))

The **T-cell receptor (TCR) recognizing peptide-MHC class II complex** is a heterodimeric, membrane-bound receptor (typically of the αβ subtype) expressed on CD4+ T cells[7]. It detects antigenic peptides (generally 13–17 amino acids) presented by MHC class II molecules, primarily on antigen-presenting cells (APCs) such as dendritic cells, B cells, or macrophages[1][4]. TCR-MHC class II engagement is essential for adaptive immune activation, leading to intracellular signaling cascades (including Ca2+-calcineurin-NFAT, PKCθ-IKK-NFκβ, RASGRP1-RAS-ERK1/2, and mTOR pathways), which drive T cell differentiation, survival, and effector function[2][6]. MHC class II restriction distinguishes CD4+ helper T cells from other T cell lineages (e.g., CD8+ cytotoxic T cells, which are MHC class I-restricted)[1][4][7]. Aberrant TCR-MHC II interactions contribute to autoimmunity, chronic inflammation, and transplant rejection, whereas therapeutic manipulation of this axis is central in cancer immunotherapy, autoimmune disease treatment, and infection control[6][3][5][8].

Other names

TCR-MHC class IICD4+ T cell receptor (in context of CD4 lineage)αβ T cell receptor (when referring to the main subtype)

Blockade or modulation of TCR-peptide-MHC class II interaction (inhibitors or therapeutic antibodies) Inhibition of downstream signaling (calcineurin, mTOR, PKCθ inhibitors) Adoptive T cell therapies (engineered TCRs specific for tumor peptide:MHC II complex)