Effect of alternating administration of PS-K and carbazilquinone in tumor-bearing mice.

In order to establish procedure for immunochemotherapy, the delayed hypersensitivity reaction (DHR) was investigated in tumor-bearing mice treated with an immunopotentiator, basidiomycetes polysaccharide (PS-K). DHR in the group given continuous administration of immunopotentiator was initially much stronger than that in the untreated group; however, the reactions were the same by the 4th week. The tumor-bearing group give intermittent administration of immunopotentiator retained strong DHR throughout the course, even though prolonged continuous administration failed to maintain such elevated immunoresponses. Alternating treatment with PS-K and carbazilquinone induced much higher DHR and much longer survival. The experimental results showed that continuous administration of an immunopotentiator led to decreasing immune responses in tumor-bearing mice. Intermittent administration of immunopotentiator was proved to be effective in restoring tumor suppression.