15 mongrel dogs receiving allografts were treated with antilymphocyte globulin (ALG; 20 mg/kg b.w. daily). The kinetics and distribution of inflammatory cells invading the transplant were analyzed by transplant aspiration cytology. Only transplant aspiration cytology enables one to observe the direct influence of ALG within the grafts themselves. Although a low-potency ALG was used, ALG-treated animals showed a significant long-term suppression of the in situ inflammation of lymphocytes (p < 0.05) and lymphoblasts (p < 0.05) during the entire experimental period. Other leucocyte populations were influenced to a lesser degree. This in situ reduction combined with a significant prolongation of graft function (p < 0.001) establishes the beneficial effect of ALG in suppressing cell-mediated immune responses in renal allografts.

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