Effect of Kp, an Antitumor Protein-Polysaccharide from Mycelial Culture of Phellinus Linteus on the Humoral lammune Response of Tumor-Bearing ICR Mice to Sheep Red Blood Cells

The immunomodulating activity of Kp, an antitumor protein-polysacchanide preparation from the shake-cultured mycelia of Phellinus linteus, was investigated in ICR mice subcutaneously implanted wit $1\times10^6$ cells of sarcoma 180. The mice were intraperitoneally administered with Kp at a does of 100 mg/kg once daily for five consecutive days starting from 24 hrs after the tumor implantation. Ten days after the last injection, the mice were immunized with $1\times10^7$ or $4\times10^8$ sheep red blood cells (SRBC) and five days later, the antibody-forming immune response were assessed by direct hemolytic plaque assay. To an immunization does of $1\times10^7$ SRBC, the Kp-treated mice elicied a successful humoral immune response despite the turmor-burden and produced $259\times10^3$ plaque-forming cells (PFC)/spleen, while the corresponding tumor-bearing control mice showed virtually no reponse $(2.0\times10^3$ PFC/spleen) (the stimulation index=129.5). However, to an immunization dose of $4\times10^8$ SRBC, both of the control mice and Kp-treated mice showed almost the same level of strong humoral immune response. From these data it is clear that Kp effectively restores the humoral immune response of the turmor-bearing ICR mice.