Abstract
The tumor-inhibiting effect of yeast cell wall (YCW) against a transplanted 3-methyl-cholanthrene-induced fibrosarcoma in C57BL/6 mice was examined alone and in combination with mitomycin-C, methotrexate or 5-fluorouracil. These drugs and/or YCW were administered intraperitoneally 3 or 5 times after tumor inoculation. While the tumorinhibiting effect of YCW alone was weak, in combination with mitomycin-C or methotrexate, it was stronger than with YCW or either of these drugs alone. Injection of 5-fluorouracil alone was as effective as in combination with YCW. These results suggest that some antitumor drugs can be augmented in their antitumor activity by combination with YCW. To investigate the effect of YCW on the immune response of mice during tumor progression, the change in mitogenic response (3H-thymidine uptake) was examined in spleen cells from tumor-bearing mice that had received YCW. The mitogenic response to bacterial lipopolysaccharide (a B-cell mitogen) was enhanced following intraperitoneal injection of YCW. The response of spleen cells from mice with tumors over 3 g to concanavalin A (a T-cell mitogen) was decreased markedly in spite of YCW-injection, while YCW augmented this response in animals with 1 g tumors.
