Mechanism in the Regulation of the Number of T Lymphocytes and Its Subsets of Normal Mice by Polysaccharides of Cordyceps Sinensis Mycelium

OBJECTIVE To study the effect of polysaccharides of Cordyceps sinensis mycelium (cordyceps polysaccharide) on the number of T lymphocytes and its subsets of normal mice and the possible mechanism.METHODS The ICR mice were randomly divided into the blank control group, positive group (lentinan 1 mg·kg^-1), cordyceps polysaccharide groups in high, medium and low dose (200, 100, 50 mg·kg^-1). After continuous celiac injection for 10 d, the number of T lymphocytes (CD³⁺ cells) and their subgroups (CD4⁺CD8^- and CD4^-CD8⁺ cells), the apoptosis rate of CD³⁺ cells in peripheral blood were detected by flow cytometry; the transformation rates of spleen lymphocyte and the expression levels of apoptosis-related genes Bcl-2 and Bax mRNA in spleen tissue were detected by real-time PCR, and the thymus index and the spleen index were measured.RESULTS Compared with the blank control group, cordyceps polysaccharide groups significantly increased spleen weight and the transformation of spleen lymphocytes in a dose-dependent manner. High dose of cordyceps polysaccharide group could obviously increase the number of CD³⁺cells and CD4⁺CD8^- cell subsets, reduce the number of CD4-CD8+ cell subsets, and significantly increase the ratio of CD4⁺CD8^-/CD4^-CD8⁺ in peripheral blood. High dose of Cordyceps polysaccharide group significantly reduced apoptosis rate of CD³⁺ cells in peripheral blood, and the transcription levels of apoptosis-related genes Bcl-2 in spleen tissue, while no significant change in the transcription level of Bax, and the Bcl-2/Bax ratio was significantly increased accordingly.CONCLUSION Cordyceps polysaccharide stimulates proliferation of mice main immune organs (spleen and thymus) and increases the number of T lymphocytes and CD4⁺CD8^- subgroup of mice. The protective mechanism suggests that cordyceps polysaccharide upregulates the transcription levels of inhibitory apoptosis gene Bcl-2 and the ratio of Bcl-2/Bax, and then inhibits the apoptosis rate of lymphocytes.