[Preventive treatment of rejection by the prolonged administration of OKT3: decrease of the immune response of the host].

Clinical use of OKT3 for the treatment of ongoing rejection episodes has already been demonstrated as being highly effective. This work shows for the first time that combining azathioprine and OKT3 was able to delay as well as to decrease both the intensity and the quality of the anti-OKT3 immunization, allowing a 1-month prophylactic use of the MoAb. It also proves that OKT3 used prophylactically during one month can lead to 4-year first cadaver graft and patient survival rates better than those ever reported with any other immunosuppressive regimen. These results were obtained with lower doses of steroids and other immunosuppressive agents than in conventionally treated control patients. After the first two injections of OKT3, tolerance was perfect allowing out-hospital administration, and side effects consisted only in an increased number of viral infections instead of the bacterial infections observed in the conventional treatment groups. The prophylactic use of OKT3 should give even better results if it were possible to reach a 1-month administration schedule in all patients by modulating the dose of OKT3 according to the T3+ cell count and the monitoring of serum OKT3 levels.