To investigate the effect of hyperbaric oxygen (HBO) on antitumor immune competence of mice with S-180 sarcoma.

186 ICR mice with S-180 sarcoma were divided into 3 equal groups: normal air(NA) group, normoxic hyperbaric nitrox group and HBO group. The activities of the natural killer (NK), the lymphokine activated killer (LAK), the cytotoxic T lymphocyte(CTL) and the abdominal cavity macrophages (M_Ø) were measured respectively by methods of 4 h release ⁵¹Cr and indirect MTT with L₁₂₁₀ as target cell. The volume and ulcerative broke rate of sarcoma and fatality of mice with S-180 sarcoma were also observed.

The activities of NK, LAK, CTL and M_Ø of mice in the HBO group were significantly higher than those without tumor in the normal control mice, and also the tumor volumes were obviously smaller, the ulcerative broke rate of tumor tissues were obviously higher and the survival time of mice were obviously longer.

HBO exposure could raise the activities of NK, LAK and CTL and strengthen the killing rate of M_Ø in mice with S-180 sarcoma, and these are part of the reasons why the growth of tumor could be inhibited.