Ex vivo detection of CD8 T cells specific for H-Y minor histocompatibility antigens in allogeneic hematopoietic stem cell transplant recipients

• We synthesized novel HLA-A2 restricted HY peptides using in silico prediction tools.
• CD137 expression was monitored on CD8+ T cells after stimulation with the HY peptides.
• We observed greater HY-specific T cell responses in A2 + FtoM recipients than controls.
• CD8+ T-cell responses to HY epitopes showed CD45RA+CD27 cytolytic effector profiles.
• This is a proof of concept for our in silico based approach of prediction of HY mHAg.

Immunologic disparities between minor histocompatibility antigen (mHAg) genes on Y (H-Y) and X (H-X) chromosomes contribute to graft-versus-host disease (GVHD) and graft-versus-leukemia (GVL) effects observed in male recipients of a female donor (FtoM) hematopoietic stem cell transplant (HCT). Using in silico prediction tools, a panel of HLA-A0201 restricted H-Y peptides was synthesized. Expression of CD137 was monitored on CD8+ T cells after brief stimulation with the H-Y peptides in FtoM HLA-A0201 HCT recipients (N = 29), and control groups (HLA-A0201 MtoM [N = 18], non-HLA-A0201 FtoM [N = 14], and HLA-A0201 female volunteers [N = 25]). Specific H-Y responses were significantly greater in HLA-A0201 FtoM than controls. CD8+ T-cell responses to novel H-Y epitopes were shared among multiple patients, showing marked CD45RA+CD27 cytolytic effector profiles. These data represent a proof of concept for our in silico/ex vivo CD8+ T-cell based approach of prediction and validation of H-Y mHAgs in HCT recipients, which may facilitate prospective studies to identify targets/biomarkers of GVHD/GVL.