patients received renal allografts and two received renal isografts from living donors. The identical twins and 34 of the other patients are still alive .Of those that died, 27 did so in the first year and three in the second year after renal transplantation. The pathological changes found in the renal allografts from 29 of these dead patients have already been published Starzl et al., 1966).The present report is a preliminary account of the light and electron microscopic changes found in biopsies obtained about two years after transplantation from 33 of the 34 surviving renal allografts and from one of the two isografts. The histopathological findings in each transplant are correlated with the relationship of donor to recipient, with the degree of compatibility of donor and recipient as shown by lymphocyte typing, with the number of clinical rejection episodes experienced by the patient, and with renal function.
MATERIALS AND METHODS
PatientsEach case is denoted by a number prefixed by the letters LD, for the allograft recipients and IDT, for the identical twin. This same code has been used previously (Starzl, 1964;Starzl et al., 1966) and further details of any of the patients can be obtained by referring to these publications.In all but two of the patients, splenectomy and bilateral nephrectomy were performed at or before the time of transplantation. The exceptions were LD2 who retained his right kidney and IDT2 in whom splenectomy was unnecessary. The thymus was removed from 12 of the patients, four before, and eight between 250-520 days after transplantation.At the time of open biopsy, the identical twin was receiving no immunosuppressive or antihypertensive drugs. Of the 33 patients with renal allo-grafts, all were being given daily azathioprine, 24 were receiving 2.5-25 mg per day of prednisone, and 15 were being treated