Abstract
Activation of cell mediated immunity of Balb/c mice was achieved by treatment with retinylacetate (A-acetate) in vitro and in vivo. In vitro, splenic cells from Balb/c mice were cultured in a microtestplate and A-acetate or A-acetate plus PHA-P was added to culture medium. After 3 days incubation ^3H-TdR incorporation to the cells was measured. Low concentration of A-acetate (10^<-8>〜10^<-7>M) induced blastoid transformation of splenic lymphocytes, on the other hand, higher concentration of A-acetate (10^<-5>〜10^<-4>M) supressed PHA induced blastoid transformation. In vivo, after 1×10^6 tumor cells were inoculated into Balb/c heteromice and nudemice, the injection of 1 mg A-acetate retarded tumor outgrowth and a combination with weekly injection of 1 mg BCG was more effective for inhibition of tumor growth in heteromice, but was not effective in nudemice. These results suggest that one of the therapeutic effects of A-acetate on tumor growth was considered to be the activation of cell mediated immunity. Furthermore, BCG is considered to generate the host antitumor immunity, thus, the combined administration of A-acetate with BCG resulted in more effective for tumor outgrowth than single administration of A-acetate.
