Background: To determine the influence of HLA mismatching on rejection after cardiothoracic organ transplantation, we analyzed results in 243 recipients.
Methods: There were 183 heart, 25 heart-lung, and 35 single lung recipients, all receiving triple-drug immunosuppression with anti-thymocyte globulin induction. Zero, one, and two mismatches occurred by chance at each locus in between 0% to 9%, 26% to 35%, and 47% to 70% of recipients, respectively.
Results: In heart recipients, compared with a two mismatch, a zero mismatch was associated with a lower linearized rejection rate in the first 6 months. A zero B locus mismatch was likewise associated with less rejection in month 1, and DR zero mismatch with reduced rejection in the first 3 months. Steroid withdrawal was more successful in those with zero mismatch at any locus. In heart-lung recipients linearized rejection was significantly lower in those with lesser degrees of A and DR locus mismatching, and after single-lung transplantation linearized rejection was significantly lower with lesser degrees of A and B locus mismatching from 3 to 6 months only. Actuarial survival did not differ for any organ with any degree of mismatch at any locus.
Conclusions: HLA mismatching affects rejection, but the effect is limited to the early postoperative period for heart and heart-lung recipients. Lower grades of mismatch increase the likelihood of successful steroid withdrawal for heart recipients. The chance occurrence of no mismatch at any locus is rare, making prospective matching infeasible. HLA mismatching identifies patients at higher risk of rejection. The best use of this information may be to guide early immunosuppression, limiting prospective matching to retransplants or with presensitized recipients.