CHARACTERIZATION OF A CYTOTOXIC FACTOR PRODUCED BY RAT BLADDER-CANCERCELL-LINE - ITS IDENTITY TO TNF-ALPHA

Clone C19 derived from a rat bladder cancer cell line BC31ad constitut ively released cytotoxic factor RCF. The serum-free C19-conditioned me dium was partially purified by DEAE-Sephacel, Sephacryl S-200 and Mono Q-FPLC chromatographies to the specific activity of 6.4 x 10(6) U/mg p rotein (LM assay). RCF was a 17-kDa protein with pI 4.6-5.0. Anti-RCF serum neutralized the cytotoxic activity of rat and mouse, but not hum an, tumor necrosis factor-alpha (TNF alpha) as well as RCF. The partia l amino acid sequence of RCF was homologous with the sequence 43-58 of rat TNF alpha. RCF and rat TNF alpha showed a similar cytotoxic spect rum against several tumor cells. Furthermore, they induced a marked pr oliferation of mouse T cells in combination with a suboptimal dose of ConA or anti-CD3 antibody, however, human TNF alpha almost not. Taken together, RCF was substantially regarded as rat TNF alpha.