HOST-SPECIFIC INTERLEUKIN-2-SECRETING DONOR T-CELL PRECURSORS AS PREDICTORS OF ACUTE GRAFT-VERSUS-HOST DISEASE IN BONE-MARROW TRANSPLANTATION BETWEEN HLA-IDENTICAL SIBLINGS

Background. Acute graft-versus-host disease (GVHD) is a serious complication of allogeneic bone marrow transplantation from an HLA-identical sibling. There is no practical test before transplantation that gives sufficient information to predict the degree of allogeneic reactivity between HLA-identical siblings. Methods. We determined the frequency with which host-specific interleukin-2-secreting donor T-cell precursors occurred in 16 consecutive pairs of HLA-identical siblings before they underwent marrow grafting. The results were correlated with the development of acute GVHD after transplantation. Results. High frequencies of host-specific T-cell precursors (greater-than-or-equal-to 1 per 100,000) were detectable before transplantation in eight donors whose siblings later had severe (grade II or III) acute GVHD. Among the donors to eight patients with mild (grade 0 or I) acute GVHD, low frequencies (<1 per 100,000) were found. Conclusions. Analysis of the frequency of such cells before transplantation may be a useful predictor of severe acute GVHD in allogeneic bone marrow transplantation between HLA-identical siblings. It is possible that the patients at risk for serious acute GVHD after marrow grafting may benefit from some alternative form of immunosuppressive therapy.