INTERFERON-GAMMA STIMULATES NEOPTERIN RELEASE FROM CULTURED KIDNEY EPITHELIAL-CELLS

The ability of cultured kidney epithelial cells (KEC) to secrete neopt erin, which is a marker of the activation of immune system was studied . In this study interferon gamma (IFN-gamma) was shown to induce neopt erin release from KEC in a dose- and time-dependent manner. Many other cytokines and mitogens (IL-1beta, IL-2, IL-6, LPS and phorbol ester) were tested for their ability to induce neopterin in KEC but all faile d to induce a significant release of neopterin from KEC. By itself TNF -alpha induced a release of small amounts of neopterin but strongly po tentiated the effect of IFN-gamma in a synergistic manner to induce ne opterin secretion. These data indicate that not only monocytes and mac rophages which it is well known secrete neopterin, but KEC are respons ible also for the high serum or urine level of neopterin observed in p atients with kidney allograft rejection or infections episodes. As the amount of neopterin released by KEC is smaller than that secreted by activated macrophages, the contribution of KEC to the overall producti on of neopterin during certain diseases may be small.