[Specific active immunotherapy of murine methylcholanthrene-induced sarcoma using a partially purified soluble tumor specific transplantation antigens].

Immunotherapeutic effects of soluble tumor specific transplantation antigens (TSTA) were studied, Crude 3M KC1 extract of C3H/He methylcholanthrene-induced sarcoma (F tumor) was purified by preparative isoelectric focusing (pIEF). The immunoprotective fraction (Fr. 15, pI 5.7-6.0) possessed about 50 fold greater activity than the crude 3M KC1 extract. Three weekly injections of optimal immunoprotective dose of Fr. 15 retarded the outgrowth of F cells and decreased the outgrowth and tumor incidence of rechallenged inoculation in mice completely resected established 1 cm tumor. Weekly injections of Fr. 15 resulted in decreased local recurrences. This therapeutic effect was immunologically specific. Fr. 15 alone did not show the therapeutic effects on the established tumor, but combined treatment with cyclophosphamide gave the increased survivals. A metastatic variant cell line (F-4) metastasized to the lung spontaneously after the resection of primary subcutaneous tumor. Therapeutic injections of Fr. 15 decreased the rates of spontaneous pulmonary metastasis of F-4. Since cross-immunoprotection tests revealed that F and F-4 share the common TSTA, the therapeutic effect of Fr. 15 upon pulmonary metastases might be due to improved host's specific immunity.