Local production of cytokines by infiltrating monocytes/macrophages and Th1 and Th2 cells is of importance in renal allograft rejection. Activated Th1 cells can produce interleukin-2 (IL-2), interferon-gamma (IFN-gamma), and tumor necrosis factor (TNF), whereas Th2 cells produce IL-4 and IL-13, which inhibit Th1 cells. Furthermore, activated T cells express the costimulatory molecule CD40-ligand. During renal allograft rejection, the chemokine RANTES is detected in both infiltrating mononuclear cells and tubular epithelium. It has been shown previously that stimulation of proximal tubular epithelial cells (PTEC) with cytokines or CD40-ligand results in production of RANTES. The present study investigates the influence of Th1 and Th2 cytokines on RANTES production by activated PTEC. RANTES was not detectable in supernatants of human PTEC stimulated with IL-2, IL-4, IL-10, or IL-13 alone. Likewise, combination of these cytokines with IL-1 alpha, IFN-gamma, or TNF-alpha, respectively, did not result in detectable RANTES production. IL-2 and IL-10 had no significant effect on RANTES production by activated PTEC. IL-4 or IL-13 in combination with IL-1 alpha + IFN-gamma or IFN-gamma + TNF-alpha resulted in a two- to fourfold augmentation of RANTES production, ranging from 2.2 +/- 0.2 to 35 +/- 2 ng/ml in different cell lines. CD40-activated PTEC stimulated with IL-4 or IL-13 produced six to ten times more RANTES (ranging from 7.9 +/- 1.9 to 62 +/- 3.5 ng/ml in different cell lines) compared with CD40-activated cells alone. Because RANTES production is augmented by IL-4 and IL-13, this study suggests that during rejection, direct cellular contact between activated Th2 cells and tubular epithelial cells amplifies the local inflammatory reaction in the kidney.