Background: Acute graft versus host disease (GvHD) remains a severe complication of allogeneic haematopoietic stem cell transplantation (HSCT). Our study summaries results of skin explant assay (SEA) as a pretransplant GvHD predictive test in a cohort of paediatric (n = 33) and adult (a = 8) patients receiving grafts from their HLA identical siblings (n = 28), haploidentical relatives (n = 3) and unrelated donors (n = 10). Results GvHD prediction are correlated with the occurrence and severity of acute GvHD posttransplant and effect of GvHD prophylaxis on GvHD clinical outcome is evaluated.
Methods and results: SEA utilises responding lymphocytes of the donor, which are sensitized firstly in vitro by mononuclears cells of patient in allogeneic mixed lymphocyte culture (MLC) and subsequently co-cultured with recipient's skin. Histopathological changes found in patients' skin explants are evaluated according to standard Lerner classification for acute GvHD. In general, GvHD predictive results in SEA correlated with GvHd clinical outcome in 28 out of 41 tested patients (68%, p = 0.015). In a cohort of HLA identical sibling transplants GvHD predictive results correlated with clinical manifestation of acute GvHD only in 15 out of 28 patients on individual GvHD prophylaxis. GvHD prophylaxis in the form of cyclosporine A (CsA) combined with short-term methotrexate (MTX) reduced the risk of acute GvHD in 10 out of 14 transplanted patients (71%) meanwhile CsA alone prophylaxis only in 1 out of 5 patients (20%). In a cohort of unrelated pairs on CsA/MTX prophylaxis combined with horse anti-lymphocyte globuline (ALG) correlated the GvHD prediction with GvHD clinical outcome (100%, p = 0.003). In all patients transplanted with the grafts from their haploidentical relatives the occurrence of severe GvHD was predicted.
Conclusion: Skin explant assay helps identify pretransplant patients at higher risk of severe acute GvHD. GvHD predictive results enable the transplantation team to individualise GvHD prophylaxis and to optimise selection of the donor.