Effects of cyclic strain on the morphology and phagocytosis of macrophages.

Morphology and phagocytosis of macrophages were studied after cultured under cyclic strain. Peritoneal macrophages obtained from 6-week old female C57BL/6J mice were attached to silicone rubber sheets, preincubated for 2 hours, and then cultured for 24 and 48 hours under cyclic strain of 5% amplitude and 1 Hz frequency (strained group) or no strain (non-strained group). Control data were obtained from 0-hour cultured cells (control group). Cell morphology was observed with optical and scanning electron microscopes, and shape index (SI) of each cell was determined from the perimeter and adhesion area. Phagocytotic activity was evaluated from the uptake of latex particles 1.5 microm in diameter. The morphology and phagocytosis of macrophages were affected by cyclic strain, although the percentage of differentiated cells was not the case. SI in the strained group was smaller than that in the non-strained group, and had a tendency of decreasing with time. Cyclic strain suppressed the phagocytosis of macrophages for latex particles, and there was a significant difference in the phagocytosis between the strained and the non-strained groups after 24-hour culture.