Sea cucumbers (or holothurians) belonging to the class Holothuroidea (Echinodermata) are marine invertebrate habitually found in the benthic areas and deep seas across the world. Many holothurians are known to be toxic. Triterpene glycosides are the main poison compounds of the sea cucumbers and play a role in the defense of holothuroids as a toxin. The triterpene glycosides are composed of a carbohydrate chain and triterpene aglycone and are widely distributed in sea cucumbers. Most aglycones have 18(20)-lactones and belong to the holostane type. Carbohydrate chains of sea cucumber glycosides have from two to six monosaccharide residues including xylose, quinovose, glucose and 3-O-methylglucose and sometimes 3-O-methylxylose, 3-О-methylquinovose, 3-О-methylglucuronic acid and 6-О-acetylglucose. They may contain one, two or three sulfate groups. At the micromolar concentrations sea cucumber glycosides show hemolytic, cytotoxic, antifungal and other biological activities caused by membranotropic action. Some sea cucumber glycosides show an immunostimulatory effect at sub-toxic nanomolar concentrations. Incubation of immune cells with the glycosides induces their activation resulting in an increase of immune cell adhesion on an extracellular matrix, enhancement of cell spreading and motility, increase of macrophage lysosomal activity, ROS formation and phagocytic activity. Injection of sub-toxic doses of some glycosides induces an increase in the number of antibody-producing plaque-forming cells in mouse spleens, an increase in the number, size and acidity of lysosomes of peritoneal macrophages, an increase of phagocytic index. It was shown that glycosides moderately induce production of some cytokines, restore the level of some CD-markers of lymphocytes, increase bactericidal activity of leucocytes and induce a significant increase in mouse resistance to lethal doses of some pathogenic microorganisms and radiation. A novel nanoparticulate antigen delivery system, tubular immunostimulating complex, consisting of cholesterol, triterpene glycoside cucumarioside A 2 -2, and glycolipid monogalactosyldiacylglycerol from marine macrophytes was developed. This complex influences cytokine mechanisms of immunological regulation and its adjuvant effect varied depending on its composition. Proteomic methods have demonstrated that the mechanism of immunomodulatory action of some sea cucumber glycosides on immune cells includes regulation of the expression of certain proteins involved in formation of the immune response. These glycosides regulate the expression of proteins associated with lysosome maturation, activation and merging, phagocytosis, cytoskeletal reorganization, cell adhesion, motility and proliferation of immune cells. It was found that the most likely membrane targets of cucumarioside A 2 -2 can be purinergic receptors of P2X family. These findings suggest that this glycoside can act as an allosteric regulator which able to withdraw purine receptor inactivation by extracellular ATP and provide a recovery ...