HLA-DR INCOMPATIBILITY PREDICTS HEART-TRANSPLANT REJECTION INDEPENDENT OF IMMUNOSUPPRESSIVE PROPHYLAXIS

To determine whether immunosuppressive prophylaxis reduces the effect of HLA-DR incompatibility on rejection, we compared clinical and immun ologic variables of patients given horse antithymocyte globulin, OKT3, or no immunosuppressive prophylaxis. Median follow-up was 27 months. Groups were similar in race; preoperative HLA reactivity; ABO matching ; number of HLA-A, -B, -C, and -DR mismatches; and rejection severity. Patients given immunosuppressive prophylaxis were younger (p = 0.04), had a greater frequency of preoperative ischemic disease (p = 0.03), and had a higher 6-month rejection rate (p = 0.02). A highly significa nt association was found between the number of mismatches at the HLA-D R locus and rejection severity (p = 0.005). Within the OKT3-based immu nosuppressive prophylaxis group and the no immunosuppressive prophylax is group a significant association was found between the number of HLA -DR mismatches and rejection severity (p = 0.01 and p = 0.009, respect ively). A similar trend was identified in the group given horse antith ymocyte globulin-based immunosuppressive prophylaxis. Logistic regress ion, used to identify independent predictors of rejection, showed that the number of HLA-DR mismatches and not the use or type of immunosupp ressive prophylaxis is significantly associated with rejection (p = 0. 0009). One-year patient survival was 83% in the group with two HLA-DR mismatches and 85% in the group with one or no HLA-DR mismatch. Thus t he lower rejection rates in patients with one or no HLA-DR mismatch we re not associated with a 1-year survival, which was better than that o f patients with two HLA-DR mismatches. The potential benefit of HLA-DR matching on rejection and patient survival must be confirmed by large r prospective studies.