A variety of cytokines and growth factors have been recently shown to modulate the growth of mesangial cells and the synthesis of the mesangial matrix. We examined chronological change of mRNA expression of interleukin-1 beta (IL-1 beta), tumor necrosis factor-alpha (TNF-alpha), transforming growth factor beta 1 (TGF-beta 1), and the platelet-derived growth factor (PDGF)-B chain in glomeruli of nephrotoxic serum nephritis using reverse transcription and the polymerase chain reaction (RT-PCR) method. Expression of TNF-alpha mRNA increased immediately after induction of nephrotoxic serum nephritis. Levels of IL-1 beta and PDGF-B chain mRNAs increased at 24 hr and remained elevated for 4 weeks. TGF-beta 1 mRNA expression increased significantly at 24 hr, peaking at 2 weeks. The chronological changes of these cytokines and growth factors were associated with two phases of inflammation in this model. Among them, expression of PDGF-B chain mRNA preceded mesangial proliferation and expression of TGF-beta 1 preceded accumulation of mesangial matrix, indicating that these two growth factors contributed to these histological alterations.