Combination therapy of radiation and SPG (Schizophyllan) in the treatment of MM46 tumor transplanted in C3H/He mice

Female C3H/He mice aged 9 weeks with transplanted MM46 tumor were used in an investigation of the administration of SPG (Schizophyllan; a glucan produced by Schizophyllum commune) combined with local irradiation with a dose of 3,000 rads. The daily dose of 10 mg/kg of SPG were injected intramuscularly for 5 consecutive days after irradiation. The antitumor effect was evaluated by the changes of tumor volume, survival curves and subsets of tumor infiltrating lymphocytes. In the group treated by a combination therapy of radiation and SPG, the tumor growth was decreased significantly as compared with the group treated by radiation therapy alone. There was no significant difference in the survival curves between these two groups. But, two of nine mice treated by radiation and SPG survived for a long time with no evidence of disease. Subsets of tumor infiltrating lymphocytes were analysed by the method of Biotin-Avidin-Horseradish Peroxidase using monoclonal antibodies. The infiltration of Thy 1.2+ (T-lymphocytes), Lyt 1+ (helper/inducer T-lymphocytes), Lyt 2+ (suppressor/cytotoxic T-lymphocytes) and MAS053+ lymphocytes (B-lymphocytes and activated T-lymphocytes) was more significant in the group treated by the combination therapy of radiation and SPG than in the group treated by radiation therapy alone. (author)