Posttransplantation cytotoxic immunoglobulin G is associated with a high rate of acute allograft dysfunctions in heart transplant recipients

Background The significance of anti-human leukocyte antigen immunoglobin G (IgG) detected in the posttransplantation course of heart graft recipients remains unclear. Method sera from 121 cardiac allograft recipients transplanted between Janu ary 1992 and December 1994 were screened for the presence of lymphocytotoxi c antibodies in the First year after transplantation. Dithiothreitol was us ed to differentiate IgG from immunoglobulin M. Results Nineteen patients (15%) had cytotoxic IgG develop, mainly during th e first month after transplantation. The percentage of women was higher in this group (42% vs 15.7%; P < .05). Donor to recipient mismatches for sex, blood typing, cytomegalovirus serology, and human leukocyte antigen typing were comparable between IgG producers and nonproducers. The frequency of ac ute allograft dysfunction during the first year after transplantation was s ignificantly higher among patients producing IgG (42% vs 5.9; P < .001). Mo st of these acute allograft dysfunctions were independent of cellular rejec tion lesions but were associated with a thickening of the posterior wall an d the interventricular septum during the acute episode. Finally, all the pa tients but one recovered. Recurrences were not uncommon and, at 1 year afte r transplantation, the dose of cyclosporine used in patients producing IgG was significantly greater, as was the left ventricular thickness. Conclusion Posttransplantation cytotoxic IgG is not uncommon and appears to be associated with a high rate of acute allograft dysfunction. Development of these antibodies can be caused by a previous undetected immunization, a s suggested by the higher percentage of women in the producer group. Correl ation with histologic lesions of humoral rejection are discussed.