Abstract
The liquid from heat-treatment of an abalone, Haliotis discus hannai, which is normally discarded as waste, was found to contain a new glycoprotein antineoplastic agent. A fraction of the liquid obtained from chromatography that was 22% carbohydrate and 44% protein was injected locally or systemically into ICR mice or BALB/c mice inoculated s.c. with allogeneic sarcoma 180 or syngeneic Meth-A fibrosarcoma, and growth of the tumors was strongly inhibited. There was an optimum dose range for the inhibition of the growth of sarcoma 180, and optimum timing. The fraction did not have antitumor activity in T cell-deficient nude mice (CD-1 nu/nu or BALB/c nu/nu mice), and administration of carrageenan in vivo decreased its activity in ICR mice. This fraction activated the cytostatic activity of peritoneal and alveolar macrophages in vivo. These results suggest that the antitumor activity is not due to a direct toxic effect but to stimulation of a host-mediated response.