RECEPTOR-MEDIATED ENDOCYTOSIS INDUCED MACROPHAGE CYTOSOLIC ACIDIFICATION AND EXOCYTOSIS
LEI Guo hua ZHANG Wei WU Jian chun PIAO Ying Jie BAO Yong yao HUANG Hui (Central Laboratory, Department of Pediatrics of Nanfang Hospital, First Military Medical University,Guangzhou 510515)
The effects of Con A, WGA, Zymosan A on macrophage cytosolic pH and outflow of lysosomal content through exocytosis were studied with SNAFL-cal-cein and FITC-Dextran on ACAS570. The results showed all three ligands could induce macrophage cytosolic acidification in about 10 min and kept at the same level hereafter; outflow of lysosomal fluorescent probe through exocytosis appeared in 15-20min. In resting conditions, macrophage lysosomes mainly distributed in cell center; after stimulated for 15 min by three ligands, the number of lysosomes increased in membrane periphery, in 25-30min lysosomes moved back toward cell center. We proposed that ligands induced lysosomal pH rises was a basic factor for outflow of lysosomal content through exocytosis, cytosolic acidification inhibited receptor-mediated endocytosis. Cytosolic acidification and outflow of lysosomal content through exocytosis were the results of cellular self-regulation and self-protection during receptor-mediated endocytosis.