Effects of sizofiran and X-ray irradiation on splenic NK activity and pulmonary metastasis in 3LL lung carcinoma-bearing mice

Intravenous injections of 3LL lung carcinoma (5 x 104) to C57BL/6 mice produced metastatic nodules of the tumor in the lungs. Splenic cells and NK activity increased with time until 11 days after the injection. In the mice treated with X-ray irradiation (3 Gy), 3 days before the injection, a larger number of metastatic nodules were observed than in mice given the tumor injection alone. Splenic cells and NK activity were reduced, with nadirs at 2 days after 3LL injection (5 days after X-irradiation). Even at 11 days, the values were low compared to non-irradiated tumor-bearing mice. Sizofiran, a 1, 3-β-glucan, given intramuscularly every other day from 3 days before the irradiation to the tumor injection, augmented the splenic cell number and NK activity at 2 days after the inoculation (5 days after X-irradiation) accompanied by a reduction of metastatic nodules at 17 days after the inoculation. These observations suggest that the anti-metastatic activity of sizofiran correlates with its NK augmenting activity in X-ray irradiated 3LL-bearing mice. (author)