Monocyte cytolytic factor in promoting monocyte-mediated lysis of bladder cancer cells by bacillus Calmette-Guerin.

The role of monocytes in cell-mediated cytolysis of bladder cancer cells was investigated. Human peripheral monocytes released a cytolytic factor which lysed T24 bladder cancer cells and a number of human tumor cells, but not normal lymphocytes or fibroblasts. After incubation of monocytes with bacillus Calmette-Guerin for 48 hr. in vitro, cytolysis of T24 cells was increased up to 56.7 +/- 4.1%. Treatment of monocytes with actinomycin D (an inhibitor of RNA transcription) reduced release of cytolytic factor from 27.3 +/- 5.7% cytolysis to 4.5 +/- 1.4% (p less than 0.05). The response to mitomycin C was different between lymphokines and monocyte cytolytic factor. The mouse monoclonal antibody against human recombinant tumor necrosis factor did not neutralize monocyte cytolytic factor. These results show that this monocyte cytolytic factor is distinct from lymphokines and tumor necrosis factor. The evidence that bacillus Calmette-Guerin increases release of monocyte cytolytic factor may be associated with anti-tumor activity of bacillus Calmette-Guerin in intravesical therapy for treatment of bladder cancer.