Human leukocyte antigen class II–Wilms' tumor 1 peptide complex (HLA-II–WT1 complex)

The Human leukocyte antigen class II–Wilms' tumor 1 (HLA-II–WT1) peptide complex is a molecular assembly consisting of a peptide fragment derived from the Wilms' tumor 1 (WT1) protein bound within the groove of an HLA class II molecule. WT1 is a zinc-finger transcription factor that is highly overexpressed in a wide range of hematological malignancies, such as acute myeloid leukemia, and various solid tumors, while maintaining very low expression in normal adult tissues. This differential expression makes the WT1 peptide, when presented by HLA molecules, an ideal target for cancer immunotherapy. Unlike HLA class I complexes which primarily activate CD8+ cytotoxic T cells, the HLA class II–WT1 complex is recognized by CD4+ T helper cells. These CD4+ cells are essential for sustaining long-term anti-tumor immunity by providing necessary signals for B-cell activation and the optimal function of CD8+ T cells. Therapeutic interventions targeting this complex, including multi-peptide vaccines like Galinpepimut-S and engineered TCR-T cell therapies, aim to harness the immune system to specifically recognize and destroy WT1-positive malignant cells.

Other names

MHC class II–WT1 peptide complexHLA-DR–WT1 peptide complexWT1-derived peptide–HLA class II complexWT1-MHC II complex

The complex acts as a ligand for T-cell receptors (TCRs) on CD4+ T helper cells. Recognition of the WT1 peptide presented by HLA class II molecules triggers the activation and proliferation of CD4+ T cells, which secrete cytokines like IFN-gamma and IL-2 to orchestrate a broader anti-tumor immune response, including the recruitment and support of CD8+ cytotoxic T cells.