Relation Between the Tumor-Specific Antigen and Cytological Characteristics in Mouse Mammary Tumors

Summary

The modal chromosome number of FM3A/B, a cultured cell line of mouse mammary tumor, is hyperdiploid. Its karyotype changed spontaneously into hypotetraploidy (FM3A/BR) during serial culture. FM3A/B and FM3A/BR were converted into ascites form (FM3A and FM3A/R, respectively). Transplantation of FM3A and FM3A/R was successful in all syngeneic C3H/He mice, with a mean survival of 26 and 23 days, respectively. Judged from cell numbers in the peritoneal cavity, growth rate of FM3A/R was more rapid than that of FM3A. Cytotoxic sensitivity of these cells was tested with syngeneic antiserum against the tumor-specific antigen of the mouse mammary tumor and with complement. FM3A/R was far more sensitive to the antibody than FM3A. The concentration of the antigens on the cell surface of FM3A/R was demonstrated by absorption tests to be 35 times higher than that of FM3A. Cytotoxic sensitivity of other mouse mammary tumors, MM102, MM2, and MM12, was also higher than that of FM3A. The chromosomal population of FM3A was 90% hyperdiploid and 10% hypertetraploid, whereas that of all other tumors was hypotetraploid.