To investigate the effect of TH-b fraction of Tetrastigma hemsleyanum on the function of dendritic cells (DC).

Peripheral blood mononuclear cells were isolated from healthy donors. DC were induced by granulocyte-macrophage colony stimulating factor (GM-CSF), interleukin-4 (IL-4), interferon-gamma (IFN-γ) and lipopolysaccharide (LPS). The phagocytosis ability of DC treated with TH-b was detected by candida spore method, the proliferation rate of lymphocyte was detected by mixed culture of DC treated by TH-b and peripheral blood lymphocyte. Surface marker CD195 and markers (CD80, CD83, CD86 and HLA-DR) of DC treated by TH-b were detected by flow cytometry. The concentration of IL-12 in DC culture supernatant was measured after TH-b treatment by enzyme immunoassay.

After 7 days culture, the expression of CD195 on DC was significantly increased compare to the base line (85.3% vs. 2.4%). The Tetrastigma hemsleyanum extract TH-b increased DC phagocytosis function, and 0.62 μg/ml was the optimal TH-b concertration to DC phagocytic ability. The expression of CD80, CD83, CD86, and HLA-DR on the surface of DC increased significantly after concluture with TH-b, The ratios of these cell markers expressed on DC were most obvious when treated with 0.62 ug/ml TH-b, and were 88.56%±8.16%, 86.75%±7.59%, 99.34%±8.24%, 96.15%±8.27% respectively, which were 71.38%±7.31%, 43.61%±4.29%, 93.41%±8.34% and 79.26%±5.12% in the control group. The treated DC (with TH-p) could strongly stimulate and promoted the proliferation of human peripheral blood lymphocyte, when coculture with lymphocyte in the ratio of 1:1, 1:10 and 1:100. The 1:1 ratio was the optimal one. After 48 hours culture with TH-b, IL-12 secreted by DC increased significantly. And when treated with 0.62 ug/ml TH-b, DC secreted the highest level of IL-12 (526.3 pg/ml), which was significantly higher than that of the control group (260.1 pg/ml) (P<0.05), and there was a concentration window phenomenon.

Low concentration of TH-b could significantly promote the phagocytosis of human DC, promote the expression of CD80 and CD86 on the surface of DC, and enhance the maturation of DC and the secretion of IL-12 in DC.