[Immunologic mechanisms of regulating calcium metabolism in human bone tissue (production of osteoclast-activating factor) during long-term anti-orthostatic hypokinesia].

During 370 days 10 healthy male subjects were exposed to antiorthostatic hypokinesia. The exposure enhanced the production of the osteoclast-activating factor (OAF) by blood mononuclear cells. The enhancement began after the 2nd month of hypokinesia and continued to increase thereafter. The index of resorption was: prior to hypokinesia--1.15 +/- 0.156, 8 months after onset--2.05 +/- 0.129, and 11.5 months after onset--2.37 +/- 0.296, the upper normal limit being 1.54. The changes were correlated with a greater amount of active T-lymphocytes in blood and a progressive increase of calcium negative balance. This investigation lends support to the previously formulated hypothesis (I. V. Konstantinova, 1986) that immunological mechanisms associated with the OAF production contribute to calcium metabolism disorders in human bone during prolonged space flights.