Antitumor effects and changes in electrophoretic mobility pattern of splenocytes and thymocytes were studied in sarcoma 180 or plasmacytoma X5563-bearing mice treated with Mitomycin C (MMC) and/or Krestin (PSK). The percentages of the inhibition of tumor growth were 80∼90% in the MMC-treated group and further improved in the MMC+PSK-treated group. In splenocyte electrophoretic pattern, intermediate mobility cells locating between high mobility cells (HMC: T cells) and low mobility cells (LMC: B cells) increased in tumor-bearer but recovered by treatment with antitumor drugs. On the other hand, in thymocyte electrophoretic pattern, LMC (immature thymocytes) which decreased by tumor-bearing were further reduced in MMC-treated group, but its reduction was suppressed by the combination with PSK. These results suggest that the combination therapy of MMC and PSK is more effective from the viewpoints of antitumor activity and antiinfectious activity because PSK restores immature thymocytes damaged by MMC.
