Delayed response to orthoclone OKT3 treatment for renal allograft rejection resistant to steroid and antilymphocyte globulin.

Since February 1986, 23 patients have received Orthoclone OKT3 treatment at our transplant center for renal allograft rejection resistant to steroids and antilymphocyte globulin (ALG). They have been followed for at least 4 months as of this study time (range: 4-15 months). We report here our experience with OKT3, including five late responders--as late as 116 days after OKT3 treatment. Overall rejection was reversed in 19/23 (83%). Rejection was controlled in 95% of primary and 50% of nonprimary transplants; 89% of the male and 80% of the female patients were treated successfully; 94% of the cadaver-donor and 80% of the living-donor transplants responded successfully. The one-year rerejection rate after OKT3 was 50%, and 38% of rerejection episodes were treated successfully. Time (days) required to reverse the episodes of acute graft rejection after the start of OKT3 is plotted, and it shows a distinctive bimodal distribution: first, early responders with a mean +/- SD of 12 +/- 5 days (range: 4-20 days) and second, late responders with a mean +/- SD of 58 +/- 31 days (range: 30-116 days). We conclude that OKT3 is very effective in treating steroid- and ALG-resistant acute rejection episodes, and also that it is important to be aware of the potential late response to OKT3 antirejection therapy and recommend delaying transplant nephrectomy or immunosuppressive withdrawal for as long as possible (probably up to 4 months) for patients who have received OKT3 treatment.