A STUDY OF COMBINED TREATMENT WITH CHEMICAL IMMUNOSUPPRESSANTS AND ANTILYMPHOCYTIC SERUM TO PROLONG SKIN ALLOGRAFT SURVIVAL

Several immunosuppressive drugs (including the methylhydrazine derivative Ro 4-6824, cyclophosphamide, methotrexate, hydrocortisone, and azathioprine) and whole body irradiation were used in conjunction with antilymphocyte serum in CBA mice grafted with BALB/c skin. Hydrocortisone and methotrexate extended the graft survival when applied after antilymphocyte serum. Radiation, cyclophosphamide, and Ro 4-6824 were more effective with preoperative administration. The most marked increase in survival time was provided by pretreatment with Ro 4-6824 followed by antilymphocyte serum. These agents acted synergistically and doubled the prolongation attributable to merely additive effects. In thymectomized mice, the combined treatment led to virtually indefinite survival. The clinical implications of these results are discussed. © 1969 by the Williams and Wilkins Co.