Mismatched Human Leukocyte Antigen-peptide complex (Mismatched pHLA)

Mismatched Human Leukocyte Antigen (HLA)-peptide complexes are specialized therapeutic targets that arise from the presentation of polymorphic or tumor-specific peptides by HLA molecules on the surface of malignant and hematopoietic cells. In the setting of allogeneic hematopoietic stem cell transplantation, these complexes—often referred to as Minor Histocompatibility Antigens (miHAs)—are recognized as foreign by donor-derived T cells, triggering a potent immune response (Goulmy et al., Nature, 1996). This recognition is the cornerstone of the Graft-versus-Leukemia (GvL) effect, which helps eliminate residual cancer cells (Bleakley & Riddell, Nature Reviews Cancer, 2004). However, if the targeted HLA-peptide complex is also expressed on non-hematopoietic tissues, it can lead to the serious complication of Graft-versus-Host Disease (GvHD). Consequently, drug development in this area focuses on identifying miHAs with expression restricted to the hematopoietic system or malignant cells to maximize the GvL effect while minimizing GvHD (Griffioen et al., Blood, 2016). Therapeutic modalities include donor lymphocyte infusions, TCR-engineered T cells, and TCR-like antibodies designed to specifically bind these pHLA complexes to induce targeted cell lysis while sparing vital organs (D'Aloia et al., Frontiers in Immunology, 2018). These targets are particularly valuable in treating hematologic malignancies where traditional chemotherapy has failed, providing a pathway for precision immunotherapy based on the genetic differences between donor and recipient.

Other names

Minor histocompatibility antigenmiHAAllo-HLA-peptide complexHematopoietic-restricted minor histocompatibility antigenMismatched MHC-peptide complexPolymorphic HLA-peptide antigen

Targeted T-cell mediated cytotoxicity via recognition of specific peptide-HLA combinations on the cell surface by T-cell receptors (TCRs) or TCR-like molecules, leading to the lysis of malignant or hematopoietic cells.