Failure of orthoclone OKT3 retreatment in a pancreas transplant recipient with antimurine antibodies.
Orthoclone OKT3 is a murine monoclonal antibody that blocks the generation and function of T lymphocytes. It has been shown to be effective in reversing acute cellular rejection in solid organ transplants. However, potential development of antimurine antibodies restricts the duration that the drug can be used and the ability to reuse the drug. The case reported in this article illustrates the failure of retreatment with OKT3 when high titer (1:3200) antimurine antibodies are present. Lack of efficacy of the drug was documented by virtually undetectable circulating OKT3 levels in plasma, no decrease in T3 lymphocytes, and organ rejection. OKT3 should only be reused when immune monitoring (antimurine antibody status, lymphocyte subsets, and OKT3 plasma levels) is performed before, during, and after its use. Patients with high-titer anti-OKT3 antibody should not be retreated with OKT3.