[Antitumor effect of LPS immobilized beads]

The anticancer effects of lipopolysaccharide (LPS) have been investigated, but its strong toxicity has made it difficult to utilize. In order to induce the anticancer effect without toxicity, LPS and its components were immobilized to polystyrene beads. Spleen cells from C3H/HeN mice and SD rats were activated by contact stimulation with immobilized beads. Cytotoxicity tests were measured by 51Cr release assay. Spleen cells stimulated by beads immobilizing a portion of the components constituting LPS led to little cytotoxicity. Spleen cells stimulated by E. coli LPS immobilized beads led to strong cytotoxicity in the murine system. On the other hand, in the SD rat system, cells stimulated with Salmonella LPS immobilized beads led to more stronger cytotoxicity than that of lymphokine activated killer (LAK) cells. These activities were enhanced by culturing within 48 to 72 hours after stimulation. Activated spleen cells were injected into the tumor-bearing mice intralesionally, and suppression of tumor growth and survival elongation of the mice were recognized. Activated cells were injected intravenously into the metastatic lung tumor-bearing rats, and lung metastasis almost vanished. LPS immobilized beads exhibited antitumor effects, and it was considered LPS immobilized beads induced killer cells through cytokines and proper immobilized LPS was different according to the species of animals.