Keyhole limpet hemocyanin peptide-MHC class II complex (KLH-pMHCII)

The Keyhole limpet hemocyanin (KLH) peptide–MHC class II complex is a multi-component immunological assembly formed when dendritic cells process the KLH protein and present its constituent peptides to CD4+ T-cell receptors (TCRs) [PMID: 10572244]. KLH is a high-molecular-weight metalloprotein from the marine mollusk Megathura crenulata that serves as a potent xenogeneic antigen, inducing strong T-cell-dependent immune responses in humans [PMID: 24551540]. This interaction is a cornerstone of clinical neoantigen testing, used to assess the integrity of the cellular immune system in patients undergoing immunosuppressive therapy or to evaluate the potency of novel adjuvants [PMID: 11043459]. In oncology, KLH is frequently conjugated to tumor-associated haptens or pulsed onto dendritic cells to enhance the immunogenicity of cancer vaccines, leveraging the robust CD4+ T-cell help generated by the KLH-pMHCII/TCR engagement [PMID: 18429243]. The complex itself is not a traditional drug target but rather a functional unit of the immune synapse that mediates the therapeutic effects of KLH-based immunotherapies, such as Immucothel for bladder cancer [PubChem CID: 11954168]. Engagement of the KLH-specific TCR triggers a signaling cascade that results in T-cell proliferation, differentiation, and the secretion of pro-inflammatory cytokines, making it a gold-standard model for studying T-cell-dependent immune responses.

Other names

KLH-pMHCII complexKLH-specific TCR-pMHC interactionKeyhole limpet hemocyanin-MHC II complexKLH peptide–MHC class II complexes on dendritic cells engaging KLH‑specific CD4+ T‑cell receptors

Antigen processing and presentation via MHC class II to CD4+ T-cell receptors, leading to T-cell activation and immune response induction.