Effect of attenuated cells on the growth of small implant of Yoshida ascites hepatoma AH109A.

The transplantability of small implants such as 10 cells of Yoshida ascites hepatoma AH109A, which grew lethally only in 2 out of 19 rats when transplanted subcutaneously, was improved by admixed implantation of attenuated tumor cells prepared with mitomycin C, presenting lethal take in 23 out of 27 animals. Similar effect was also obtained by liver homogenate or sonicated tumor cell suspension. Although the rate of tumor "take" of less than 10(3) cells of AH109A inoculated in the subcutis increased by admixing the attenuated cells, growth characteristics of such a small implant of the tumor, once initiated, were not significantly different whether inoculated with or without the attenuated cells. Growth support effect of attenuated cells was discussed in relation with either the size of inoculum or growth ability of tumor cells.