Effects of photochemical donor pretreatment on the pattern of dog renal allograft infiltrating cells

Kidneys were removed ten minutes after treating the donor with 1 mg of 8-methoxypsoralen per 1 kg b.w., during hypothermic preservation UVA-irradiated (intensity: 1.34 mJ/s) for 4 h and thereafter transplanted into ASDI dogs (n=10). Fine needle aspiration biopsies were performed to analyze the inflammatory response. In comparison with untreated ASDI dogs (n=9) PUVA pretreated renal grafts showed three important differences: 1. At the peak of the rejection process in the control group (day 8) the cellular infiltrate in the PUVA-pretreated kidneys was significantly diminished. 2. This reduction was caused by a significantly lower influx of monocytes/macrophages. 3. The peak of the cellular response in the PUVA group was delayed. These findings support the concept of reduced graft immunogenicity by pretransplant PUVA treatment.