Major histocompatibility complex, class I, E (HLA-E) restricted CD8+ regulatory T cell pathway (HLA-E/CD8+ Treg pathway)

The Major histocompatibility complex, class I, E (HLA-E) restricted CD8+ regulatory T cell pathway is a specialized immune regulatory mechanism essential for maintaining peripheral tolerance and preventing autoimmunity. HLA-E is a non-classical MHC class Ib molecule that presents conserved peptides—typically derived from the leader sequences of other MHC class I molecules—to the T-cell receptors (TCRs) of a specific subset of CD8+ regulatory T cells (Tregs) [PMID: 22195746]. These CD8+ Tregs recognize HLA-E/peptide complexes on the surface of activated, potentially autoreactive CD4+ T cells and subsequently suppress or eliminate them to prevent excessive immune responses [PMID: 15123308]. In the context of oncology, many tumors overexpress HLA-E to exploit the inhibitory NKG2A receptor on NK cells and CD8+ effector T cells, effectively evading immune surveillance [PMID: 30531905]. Conversely, dysfunction in this pathway is linked to autoimmune diseases such as multiple sclerosis, where the failure to regulate self-reactive T cells leads to chronic inflammation [PMID: 18424730]. Therapeutic strategies include the use of checkpoint inhibitors like monalizumab, which blocks the HLA-E/NKG2A interaction to boost anti-tumor activity, and experimental approaches aimed at enhancing CD8+ Treg activity for treating autoimmune disorders [PMID: 30531905].

Other names

HLA-E restricted CD8+ suppressor T cell pathwayQa-1-restricted CD8+ T cell pathwayHLA-E/NKG2A axisCD8+ regulatory T cell-mediated suppression

Monalizumab is a monoclonal antibody that blocks the inhibitory interaction between HLA-E and the NKG2A receptor on NK cells and CD8+ T cells, thereby enhancing anti-tumor immunity. In the context of regulatory T cells, the pathway involves the T-cell receptor (TCR)-mediated recognition of HLA-E/peptide complexes on target cells (such as activated CD4+ T cells), leading to their suppression or lysis to maintain immune balance.