OBJECTIVE To define the involvement of tumor necrosis factor (TNF) in renal interstitial fibrosis. METHODOLOGY Renal fibroblasts and tubular cells were cultured and characterized. Cell proliferation was measured by 3H TdR uptake assay. The effect of TNFα on renal fibroblasts proliferation was evaluated after the addition of 5μg/L or 40μg/L of TNFα. The expression of TNFα and its receptor 1 mRNAs in cultured tubular cells were identified by RT PCR. Cellular form of TNFα and TNFα released from cultu...