Experiments have been performed to examine the phagocytosis of human blood leucocytes on which high hydrostatic pressure has been applied.
The results were as follows: 1) At 50-100 atm. pressure, there was no difference in phagocytes number against control for 30-60 min., but increase for 120 min. 2) At 200-2000 atm. pressure, the difference in phagocytes number was found as compared with control for 30-120 min. The higher the pressure was, the less phagocytes was. 3) The rate of phagocytosis average degree showed a tendency to be same with the rate of positive degree of phagocytosis. 4) At one atmospheric pressure, monocytes have the most powerful phagocytic activity, then come neutrophilic, eosinophilic leucocytes and lymphocyte in the order of their phagocytic activity. Especially, lymphocytes show no fluctuation on the rate of positive degree of phagocytosis for almost any time under pressure. Phagocytosis of lymphocytes has not been effected by pressure. 5) Phagocytic activity of monocytes and neutrophilic leucocytes have been influenced by pressure, but eosinophilic leucocytes and lymphocytes less than the two formers. 6) It was discussed whether the effect of high hydrostatic pressure on phagocytosis of leucocytes is caused by the alternation of the surface tention between leucocyte and its surrounding medium, and the streaming of leucocytes protoplasma. 7) For the soap solution-petroleum system, the interfacial tention decreases under pressure (0-500 atm.).