earticle

영어

Capsular polysaccharides (CPSs) of Streptococcus pneumoniae are representative T-lymphocyte independent type 2 (TI-2) antigens, causing the immune escape from the host and majority of meningitis in human adults. However, the detail mechanism of this immune escape by S .pneumoniae has been poorly understood. Serotype 14 CPS taken by SIGN-R1+ macrophages in the splenic maginal zone is regurgitated to follicular dendritic cells (FDCs). It was consistent with polysaccharide dextran, another ligand for SIGN-R1, and its regurgitation was confirmed in SIGN-R1 transfectants in vitro. While understanding the regurgitation of dextran, we found that SIGN-R1 bound to Binding immunoglobulin protein (BiP), a well-characterized endoplasmic reticulum (ER) chaperone, primarily on the cell surface. Furthermore, SIGN-R1+ macrophages in the maginal zone showed the higher expression of BiP than other macrophages in the red pulp, implying the important role of SIGN-R1 binding to BiP in vivo. Surprisingly, after the treatment of dextan in vitro or in vivo, dextran was rapidly translocated into the ER membrane and subsequently regurgitated here, depending on SIGN-R1 and complement C3. Therefore, these results demonstrated that the interaction of SIGN-R1 with Bip mediates the regurgitation of polysaccharide dextran through the ER membrane, demanding further studies to understand the reasons of the non-immunogenecity of bacterial polysaccharides.