Complete donor chimerism is a prerequisite for the effect of Predicted Indirectly ReCognizable HLA Epitopes (PIRCHE) on acute graft-versus-host disease.

Predicted indirectly recognizable HLA epitopes (PIRCHE) computationally predict donor T-cell recognition of mismatched-HLA derived peptides following allogeneic haematopoietic stem-cell transplantation (allo-HSCT), as is evidenced by the correlation between presence of HLA-DPB1-derived PIRCHE and the occurrence of graft-vs.-host disease (GVHD). Complete donor T-cell chimerism associates with an increased GVHD risk compared to mixed patient and donor chimerism.