Mutagenic activity of tumor-associated macrophages in Salmonella typhimurium strains TA98 and TA 100.

Suspensions of cells from a series of strain BALB/cfC3H mouse mammary tumors, and adherent and nonadherent cells from the tumors, were tested for their ability to increase the mutation rate of Salmonella typhimurium tester strains TA98 and TA100. Significant increases were seen with cells from three of four tumor lines tested on the TA98 strain and with one of four tested on the TA100 strain. The mutagenic activity was due primarily to cells in the adherent fractions which were greatly enriched for macrophages.