[Antitumor immunity transfer by a factor isolated from lymphocytes of tumor bearer]

Low-molecular extracts (LMEs) of lymphocytes were obtained from spleen of noninbred rats using our experimental model of intraorganic growth of Guerin's carcinoma. They were intended to transfer immune reaction to tumor antigens in vitro. It was LMEs developed prior to tumor progression in spleen that showed immunospecific activity with respect to tumor cells. Also, they had marked antigen-independent immunopharmacological activity. Single intravenous injection of LMEs100 pg given on day 7 of tumor growth stimulated antitumor resistance in intact rats within a short time. It prevented tumor cells engrafting in 60% of tumors. A tumor-specific factor has been evolved capable of immune reaction transfer to tumor antigens in vitro thus preventing tumorigenesis in recipients in vivo.