Analysis of Mucosal Immunity by the Fc receptor for IgA and IgM

点击翻译按钮获取中文摘要

We previously identified an Fc receptor for IgA and IgM (Fcα/μ receptor), which is expressed on antigen presenting cells. We found that the Fcα/μ receptor mediated endocytosis of IgM immune complex with antigen, such as staphylococcus aureus, suggesting an important mechanisms of pathogen eradication by IgM. The present study aims to clarify a role of the Fcα/μ receptor in mucosal immunity. We have identified several isoforms of the soluble Fcα/μ receptor expressed on intestinal Paneth cells and epithelial cells of urinary tract. We found that the extracellular domain of the isoforms may have antimicrobial activity against E.coli. Furthermore, we observed that mice deficient in the Fcα/μ receptor gene exhibited high IgA concentration in both serum and fecus and the presence of many IgA producing cells in lamina proplia.We also observed that the Fcα/μ receptor was strongly expressed on the area of germinal center. Immunohistochemical study revealed that FDC substantially expressed the Fcα/μ receptor in germinal center. These results suggest that the Fcα/μ receptor regulates IgA production in peyel's patches and/or intestinal flora by the soluble Fcα/μ receptor secreted from Paneth cells. Furthermore, we studied the mucosal immune responses by antigen challenge in mice deficient in the the Fcα/μreceptor gene.