EFFECTS OF LANKACIDIN GROUP (T2636) ANTIBIOTICS ON THE TUMOR GROWTH AND IMMUNE RESPONSE AGAINST SHEEP ERYTHROCYTES IN MICE

Antitumor and immunosuppressive activities of some lankacidin group (T2636) antibiotics were investigated in vivo and in vitro. Lankacidin-C, Lankacidin-C 8-propionate, and Lankacidin-C 14-propionate, given intraperitoneally, showed inhibitory effects at doses ranging from 25 to 1, 000mg/kg on the growth of the following tumors; leukemia L-1210, lymphosarcoma 6C3HED/OG sensitive to l-asparaginase, and melanoma B-16 in mice. Leukemia L-1210 cells resistant to 6-mercaptopurine or to cytosine arabinoside were also sensitive to the antibiotics. Lankacidin-C 8-propionate and Lankacidin-C 14-propionate inhibited the proliferation of HeLa cells in concentrations of more than 50μg/ml in vitro, whereas Lankacidin-C was not inhibitory. Lankacidin-C at high doses suppressed the production of antibody against sheep erythrocytes in mice when administered before or after antigenic stimulation. On the contrary, Lankacidin-C 8-propionate slightly suppressed the anibody production only after antigenic stimulation, and Lankacidin-C 14-propionate had no suppressive activity in any conditions.