The incidence of antibody formation to OKT3 consequent to its use in organ transplantation

Enzyme-linked immunosorbent assays were performed on 12,133 serum samples to determine the incidence of anti-OKT3 antibody formation among transplant recipients who had received OKT3 for rejection treatment or prophylaxis. High anti-OKT3 antibody titers (> or = 1:1000) were detected in 5.8% of samples drawn 2 to 8 weeks following initiation of OKT3 therapy. The frequency of high titers differed by organ (6.9%, 2.7%, and 5.3% for kidney, heart, and liver, respectively; P < 0.001) and by sampling times (P < 0.001). The highest frequency of positive titers was obtained in samples obtained between 2 and 4 weeks following the initiation of OKT3. For all transplant recipients and for kidney recipients alone, multivariate logistic regression showed that the risk of high anti-OKT3 titers varied significantly at 2 to 4 weeks and at 4 to 6 weeks (but not at 6 to 8 weeks) with age (the youngest patients had the highest incidence, with a steady decline after age 30; P < 0.05), course of therapy (lowest frequencies followed a first course of OKT3; P < 0.001), and transplant number (lowest frequencies followed a first transplant; P < 0.01). Analyses of a set of patients on whom immunosuppressive regimen information was available indicated that prophylactic or maintenance treatment with CsA was associated with a significantly lower frequency of high-titer anti-OKT3 antibodies than was therapy without CsA (P < 0.001). In conclusion, this series provides confirming evidence that high-titer anti-OKT3 antibodies, which are of concern whenever retreatment with OKT3 is contemplated, occur in a low percentage of patients and are associated with such factors as age, previous transplantation or courses of therapy with OKT3, and treatment with CsA.