Clinical relevance of GSTT1 mismatch in solid organ and hematopoietic stem cell transplantation

Since 2001, year in which Glutathione S-transferase theta class 1 (GSTT1) gene appeared to be related to the occurrence of de novo immune hepatitis after liver transplantation, this gene with two allelic variants, GSTT1∗A (wild type copy) and GSTT1∗0 (deletion copy), has emerged as a potent histocompatibility antigen. Namely, a donor-recipient liver graft combination of a GSTT1-negative recipient (homozygous for GSTT1∗0) and a GSTT1-positive donor results, very frequently, in the appearance of a severe immune-related graft hepatitis with production of IgG anti-GSTT1 antibodies. In kidney transplantation, GSTT1 donor-recipient mismatch is also associated with production of anti-GSTT1 antibodies and antibody-related rejection episodes with C4d deposition in graft biopsy. The more recent discovery of anti-GSTT1 antibodies in hematopoietic stem cell transplantation, clearly confirms a role of GSTT1 as histocompatibility antigen in this setting. Interestingly, the consequences of GSTT1 mismatch might be either rejection or graft-versus-host disease, depending on the GSTT1 mismatch's sense of direction. The involvement of GSTT1 in immunological allo-recognition is unquestionable although there are still many aspects that remain to be explored.