OKT3 therapy for hepatic allograft rejection: Differential response in adults and children

The clinical courses following OKT3 therapy for hepatic allograft rejection (HAR) in adults and children have not been individually defined. We have reviewed our experience with OKT3 therapy for HAR in adults and children to compare: (1) the initial response to OKT3 therapy, (2) the clinical course following OKT3 therapy, and (3) the antimurine antibody response and immunologic monitoring results. Children required OKT3 therapy more frequently than adults: Fourteen courses of OKT3 therapy were required in 130 orthotopic liver transplants (OLT) in 108 adult patients, whereas nineteen courses of OKT3 therapy were required in 94 OLT in 78 children (P<0.02). Repeat OKT3 therapy was not required in adults-however, four of nineteen courses of OKT3 therapy in children were repeat OKT3 therapy for rejection. No differences existed between adult and pediatric treatment groups with respect to number of prior OLT procedures, previous graft loss to rejection, percentage of ABO-incompatible grafts, frequency of positive donor-recipient lymphocyte crossmatches, or time to first rejection. The initial response to OKT3 therapy (rapid reversal, delayed reversal, and failure) was remarkably similar in adults and children. However, nine of 13 (70%) children with clear evidence of response to OKT3 treatment experienced breakthrough rejection or early recurrent rejection, whereas none of 12 adults suffered breakthrough rejection or early recurrent rejection (PcO.Ol). Early recurrent rejection did not correlate with delayed reversal of rejection, early return of CD3⁺cells by peripheral blood monitoring, or development of anti-OKT3 antibodies. All 4 courses of OKT3 retreatment in children were successful in reversing rejection, and breakthrough rejection and early recurrent rejection did not occur. Overall graft and patient survival in pediatric patients requiring OKT3 therapy (67% and 73%) was not different from that in adults (71% and 79%). Results obtained in one patient provide the first evidence that successful OKT3 retreatment of HAR can be achieved in the presence of preexisting idiotypic anti-OKT3 antibody. In conclusion, OKT3 therapy for HAR was required more frequently in children than in adults. The clinical outcome following OKT3 therapy for HAR also differs markedly, with early recurrent rejection and breakthrough rejection occuring more frequently in children.