Effectiveness of a second course of OKT3 monoclonal anti-T cell antibody for treatment of renal allograft rejection.

A second course of OKT3 monoclonal anti-T cell antibody was given to 21 recipients of kidney transplants. Rejections reversed in 43% of patients in whom 95% of rejections had reversed with their initial OKT3 course. Reversal was highly dependent upon the timing of rejection, anti-OKT3 antibody production, and T cell CD3 modulation. Rejections treated greater than 90 days after transplantation were resistant to OKT3 reversal. High-titer anti-OKT3 antibodies prevented OKT3 reversal of rejection, and effective CD3 (the cell surface target of OKT3) modulation was necessary for successful OKT3 reversal of rejection. Reexposure to OKT3 further stimulated anti-OKT3 antibody production and broadened the specificity of the antibodies produced. OKT3 can effectively and safely be used a second time for treatment of early T cell-mediated renal allograft rejections if high-titer anti-OKT3 antibodies have not been made.