Antibody response to OKT3 and methods for monitoring.

Monitoring the antibody response to OKT3 is essential. Retreatment with OKT3 can be accomplished successfully in the great majority of patients. It is important to know the patient's peak antibody status before and during retreatment. Patients with no anti-OKT3 antibodies, or with low-titer (< or = 1:100) antibodies, especially if these do not include anti-idiotypic antibodies, have retreatment success similar to that of patients undergoing primary treatment with OKT3. In contrast, patients with high-titer (> or = 1:1000) antibodies should be treated with immunosuppression other than OKT3. Methods for monitoring the OKT3 antibody response have progressed, allowing one to estimate the titer and specificity (anti-idiotype and/or anti-isotype) in a timely fashion. Improvements still must be made in the area of standardization, so that results between various transplant centers can be more accurately compared.