The Study on the Recognition of Apoptotic Thymocyte by Macrophage

Moon, Yong Suk; Kim, Bong Seon; Kim, Jae Bong; Um, Kyung Il

Abstract

The present study was carried out to investigate the correlation with the sugar specificity of the apoptotic cells and the phagocytosis of the macrophage. Young rat thymocytes were isolated from the thymus and macrophages were isolated from the peritoneal cavity. Isolated thymocytes were treated with dexamethasone to induce apoptosis. After identified the apoptotic cells by TUNEL method, nine kinds of lectins (PSA, UEA I, GSL I B4, ECL, DBA, SBA, DSL, GSL II or WGA) were used to investigate the sugar specificity of the apoptotic thymocyte. And we carried out the phagocytosis assay using the lectin-inhibitory sugars. By TUNEL method, the most numbers of apoptotic thymocytes were observed in the cultured thymocytes treated with 10(-6)M of dexamethasone for 6 hours. From lectin histochemistry, apoptotic thymocyte showed positive reaction with PSA, UEA I, SBA, DSL and WGA, which indicate apoptotic cells have the sugar residues of alpha-D-mannose, alpha-L-fucose, terminal beta-N-acetylgalactosamine and internal beta-1, 4-N-acetylglucosamine oligomers. From phagocytosis assay using cultured thymocytes and macrophages, apoptotic thymocytes of positive reaction with TUNEL method were phagocytosed by macrophage. When the apoptotic thymocytes treated with the lectin-inhibitory sugars were mixed with the macrophages, it was observed that the phagocytosis of macrophages was reduced by methyl-alpha-mannopyranoside and alpha-L-fucose. Considering overall results, it can be assumed that the mannose and fucose may play an important role in the recognition of apoptotic thymocytes by macrophages.