[Effect of decompression on the compliment system].

Decompression effects on the complement system were studied in healthy male volunteers who made 39 "ascents" to 7000-9000 m and 13 "descents" to 30 m. Hemolytic activity of the complement system components was determined in the blood serum taken from the cubital vein of the subjects immediately before and after decompression. The results of this study showed that in the absence symptoms of decompression sickness (DCS) and doppler-detected gas bubbles (GB) the subjects reduced activities of C1 and C4. In the event of altitude joint pains the activity of the complement system components was significantly unchanged. In subjects with circulating GB the complement status was more markedly altered following simulated descents rather than ascents pointing to an alternative activation of the system. Subject with the skin DCS had a two-fold reduction of the complement system activity by the alternative mechanism and a reduction of C5 activity whereas there were no changes in the activities of C1, C2, C3, C4, CH50. It is concluded that alternative activation of the complement system may be involved in the genesis of those DCS forms whose emergence relates to gaseous embolism of veins and pulmonary capillaries.