GAMMA-INTERFERON GENE-EXPRESSION IN HUMAN RENAL-ALLOGRAFT FINE-NEEDLEASPIRATES

Cytokines appear to play a major role in acute transplant rejection (A R); however, the specific cytokines initiating AR are not known. To in vestigate gamma-interferon messenger RNA (mRNA) as a key factor in AR induction, we performed reverse transcription-polymerase chain reactio n (RT-PCR) on renal allograft fine needle aspirates (FNA). Fifteen FNA hom 15 patients were processed and interpreted in the standard fashio n, the percent of tubular cells with MHC class II expression (DR) quan titated, and aliquots of FNA obtained for RT-PCR. RT-PCR was performed with primers to gamma-IFN with cyclophylin and insulin primers as con trols. Retrospective clinical diagnoses were made for each FNA sample. Following RT-PCR, all FNA and FNAs hom control normal and AR nephrect omy specimens had cyclophylin present, and in the 9 samples tested ins ulin was absent. Five patients had AR clinically and by FNA criteria; all 5 had elevated DR and gamma-IFN mRNA present in FNA. Five patients had tubular necrosis or cyclosporine toxicity clinically, and FNA wit hout immune activation or elevated DR and negative gamma-IFN mRNA Two patients had immune activation by FNA with elevated DR; both FNA expre ssed gamma-IFN mRNA by Southern blot, one only weakly, and both patien ts subsequently developed clinical AR. Two patients had recently treat ed AR, one with persistent DR elevation without immune activation and negative gamma-IFN mRNA in FNAs. This study demonstrates that RT-PCR c an be performed with renal allograft FNA samples. The findings suggest intragraft gamma-IFN mRNA expression occurs in active AR preceding cl inical AR, thus defining incipient AR. Detection of gamma-IFN mRNA may offer an early diagnostic tool for detection of AR