Primary human keratinocytes as targets in predicting acute graft-versus-host disease following HLA-identical bone marrow transplantation

Graft-versus-host-disease (GVHD) remains a major problem following allogeneic bone marrow transplantation (BMT) and manifests itself mainly by damage to epithelial cells of the skin, gut and bile ducts. Reliable tests to predict GVHD are lacking. We developed an assay in which donor T cells are stimulated by patient keratinocytes (KCs), compared that with stimulation by patient peripheral blood mononuclear cells (PBMCs) and studied the relationship to GVHD. In 27 patients undergoing HLA-identical BMT for haematological malignancies, donor T-cell reactivity was determined as the helper T-lymphocyte precursor (HTLp) frequency against host PBMCs (25 patient-donor pairs) and host KCs (20 patient-donor pairs). KCs were obtained by shave biopsies and cultured with interferon (IFN)-gamma to induce HLA class II expression. In assays using patient KCs and donor T cells, anti-CD28 antibody was added to compensate for the lack of co-stimulatory molecules on KCs. Results were related to the occurrence of GVHD. As BMTs were performed with partially T cell-depleted grafts, GVHD was limited to grade 0 (five patients), grade I (seven patients) and grade II (12 patients). No differences were found in donor T-cell reactivity to patient PBMCs, as expressed as HTLp frequency in patients with or without GVHD. However, significant differences (P < 0.01) were found in donor T-cell reactivity to patient KCs when comparing patients with and without GVHD. Donor HTLp frequencies against patient KCs give a better prediction of GVHD than those against patient haemopoietic cells following HLA-identical BMT, which may indicate that at least some minor non-HLA histocompatibility antigens present on KCs are different from those on haemopoietic cells.