RESUMO
Polyactin A is a polysaccharide extracted from cultured alpha-Streptococcus No. 33 in the mouth. It is also known as alpha-glucomannan. According to clinical reports, Polyactin A is considered to be an immunological adjuvant with significant curative effect in chemotherapy of tumors. Immunological activities of Polyactin A were studied. When injected into mice at the dosage of 100 mg/kg for 4-5 consecutive days, Polyactin A can cause a marked increase in spleen weight and RFC in spleen, and it can antagonize the immunosuppressive actions of cyclophosphamide. Polyactin A can also increase phagocytosis of macrophages in the peritoneal cavity of mice. Phagocytotic ratio and phagocytotic index in the experimental group were greater than those in the control group. Phagocytotic ratio and phagocytotic index were respectively 63.5 +/- 8.3% and 1.02 +/- 0.05% in the Polyactin A treated group but were respectively 21.0 +/- 5.7% and 0.3 +/- 0.03% in the control group. The differences were significant (p < 0.05, < 0.01). Polyactin A had definite influence on the transformation test of lymphocytes and increased the transformation ratio of lymphocytes in vitro. The ability of Polyactin A to induce the transformation of lymphocytes into lymphoblasts was almost the same as that of PHA. These results suggest that polyactin A has a marked immunological activity, which is not entirely due to the role of large molecular weight polysaccharide. They provide direct evidence for the assumption that Polyactin A may be an immunological adjuvant, and it is experimentally confirmed that Polyactin A can protect the immunity of the organism.