To investigate the immunomodulatory effects of sea cucumber oligopeptides and their mechanisms, a total of 250 specific pathogen free (SPF) female BALB/c mice are randomly divided into 5 groups:the control group, the whey protein group (with 0.30 g/kg of whey protein) and the groups with 0.15, 0.30 and 0.60 g/kg of sea cucumber oligopeptides. The experiment takes 30 days. To determine the cell-mediated immunity, the humoral immunity, the macrophage phagocytosis and the natural killer (NK) cell activity in mice, the splenic lymphocyte proliferation and the delayedtype hypersensitivity assays (for the cellmediated immunity), the IgM antibody response of spleen to sheep red blood cells (SRBC) and the serum hemolysin level assays (for the humoral immunity), the carbon clearance assay and the phagocytic capacity of peritoneal cavity phagocytes assays (for the macrophage phagocytosis) and the NK cell activity assays are performed. Furthermore, the flow cytometry is used to determine the T lymphocyte subsets. The results showed that the sea cucumber oligopeptides significantly increase the cellmediated immunity, the humoral immunity, the macrophage phagocytosis and the NK cell activity in mice(P<0.05), and the effects are better than those of the whey protein. From the flow cytometry, it is observed that the sea cucumber oligopeptides significantly enhance the percentages of CD3⁺ and CD4⁺ (P<0.05). In conclusion, the sea cucumber oligopeptides could increase the T lymphocyte cell number and the Th cell proportion to enhance the functions of the cellmediated immunity, the humoral immunity, the macrophage phagocytosis and the NK cell activity, and furthermore to improve the immune functions in mice.

sea cucumber oligopeptides  /  immune function  /  cell-mediated immunity  /  humoral immunity  /  macrophage phagocytosis  /  natural killer cell activity  /  T lymphocyte