Although prostaglandins (PG) are recognized to be regulators of renal function, their importance in renal allograft rejection has not been clearly defined. Pilot studies of acute renal allograft rejection in the dog have identified aberrations in PG metabolism, manifested by marked increases in TxB2:PGI2 ratios. This proposal investigates PG production by both the cyclooxygenase [thromboxane (TxA2), prostacyclin (PGI2), prostaglandin E (PGE2)] and lipoxygenase [hydroperoxyarachidonic acid (HPETE)] pathways during renal allograft rejection and compares levels of these arachidonate metabolites with changes in renal function and alterations in immunologic reactions. Concomitant immunologic monitoring will focus on T-lymphocyte function in the renal allograft, spleen and blood using the one way mixed lymphocyte reaction (MLR), cell mediated cytotoxicity assay (CMC) as well as interleukin 2 (IL2) production by helper T-lymphocytes (HTL) and IL2 utilization by cytotoxic T-lymphocytes (CTL). It is anticipated that increased production of lipid hydroperoxides such as HPETE (a PGI2 synthetase inhibitor), will account for a decrease in renal PGI2 levels and that the prostaglandin-eicosanoid system will be demonstrated to be an important link between the immune response and the final destruction of the kidney during acute allograft rejection. A standard dog renal allograft model will be used to study products of arachidonic acid metabolism in the kidney. Initially, studies will involve in vitro tissue slice incubation, and later in vivo renal vein and urine sampling, using chromatographic and radioimmunoassay techniques. It is hypothesized that restoration of the normal balance between TxA2 (a potent vasoconstrictor and platelet aggregator) and PGI2 (opposite effect) by increasing PGI2 production (Nafazatrom), inhibition of the lipoxygenase pathway (nor-dihydroguaiaretic acid), and/or inhibition of thromboxane synthetase (UK-38,485) will prevent, attenuate, or delay the hemodynamic and excretory changes that accompany renal allograft rejection. This has potential utility in that immunologic tolerance for the graft could develop in time with or without special immunologic manipulations if renal iability is maintained by preservation of renal blood flow during the """"""""adaptation"""""""" period. Correlation of alterations in the immunologic response (T-cell function) with changes in renal PG metabolism may contribute to an understanding of the complex entity of renal allograft rejection. Also observing the changes in arachidonate metabolism in this model of intense accelerated renal injury should provide insight about the role of the prostaglandin-thromboxane-eicosanoid system in other forms of renal disease.
