Epidermal damage in skin of allogeneic marrow recipients: relative importance of chemotherapy, conditioning and graft v. host disease.

The relative importance of previous chemotherapy, conditioning and graft v. host disease in producing the epidermal damage associated with allogeneic bone marrow transplantation was investigated by enumerating individually necrotic cells. A small number was seen in many pre-transplant biopsies and was related to the time interval between biopsy and the last dose of chemotherapy. Their presence did not predispose patients to develop graft v. host disease in the post-transplant period. In post-transplant patients without rashes the degree of epidermal damage at 14 days was similar to that seen in the pre-transplant period indicating that the effects of the conditioning regime were insignificant. In patients with rashes clinically classical of graft v. host disease, necrotic cells were increased above the pre-transplant levels even in the absence of a lymphocytic infiltrate. Lymphocytic infiltration was seen more frequently in biopsies taken later after transplantation and after the onset of the rash and was associated with the maximal amount of epidermal damage. Comparison of the degree of epidermal damage in pre- and post-transplantation specimens lacking a lymphocytic infiltrate resulted in the correct identification of the majority of patients with clinical evidence of graft v. host disease. This approach may, thus, be useful in diagnosing early graft v. host disease especially if combined with keratinocyte HLA-DR staining.