PATHOLOGICAL CHANGES IN SIX TREATED BABOON‐TO‐MAN RENAL HETEROTRANSPLANTS

Six baboon‐to‐man renal heterotransplants, each consisting of a pair of kidneys, were examined. Two had been removed from their recipients at forty‐nine and sixty days after transplantation because of the ever‐increasing doses of immunosuppressive drugs needed to control rejection; the other four pairs of kidneys were examined after death of the recipients at nineteen, twenty‐three, thirty‐five, and forty‐nine days. All the kidneys were enlarged. On the subcapsular surfaces of one pair there were petechias; four were mottled with irregular haemorrhages and infarcts; one pair had undergone almost complete hemorrhagic infarction. The transplants were heavily infiltrated with plasma cells, lymphocytes, large pyroninophilic lymphoid cells and eosinophils. Mitoses, “LE” cells and erythrophagocytosis were seen. Associated with this infiltration there was rupture of peritubular capillaries, interstitial cedema and widespread tubular damage. Fibrinoid necrosis of the walls of arterioles and interlobular arteries, with narrowing and obstruction of some vessels by fibrin and platelet deposits on the intima were common in all except one pair of kidneys. Associated with these vascular lesions there were focal infarcts and extensive interstitial haemorrhages. All the histological changes were more severe than those seen either in treated human renal homotransplants or in a comparable series of chimpanzee‐to‐man renal heterotransplants where cellular infiltration was slight and vascular lesions only present at the height of rejection. This work was aided by grants A‐6283, A‐6344, HE‐07735, AM‐07772, A1‐01452, and OG‐27 from the U.S. Public Health Service, and by a grant from the Medical Research Council. We would like to thank Drs D. Baitlon, J. Gordon, R. B. Hill, D. Lang, and D. E. Smith who performed the autopsies on these cases. We are particularly grateful to Dr D. T. Rowlands, who supervised most of the autopsies, for his helpful co‐operation throughout this study. Expert assistance in preparing the sections and photomicrographs was given by Miss Jane Rendall. © 1965 BJU International Compan