Fcα/μR, a novel Fc receptor for innate antibodies IgM and IgA

Natural antibody that mainly belongs to IgM class is involved in the prevention of pathogen dissemination to vital organs. However, it has been a mystery how it protects us against infection. We previously identified a novel Fc receptor for IgM and IgA, designated Fcα/μ receptor (Fcα/μR), which might be involved in IgM-mediated immune defenses against infection. Fcα/μR is a new member of Fc receptors family on the chromosome 1. The Fcα/μR is constitutively expressed on the majority of B-lymphocytes and macrophages. The Fcα/μR mediates endocytosis Staphylococcus aureus/anti-S. aureus IgM antibody immune complexes by B-lymphocytes. These results reveal a new mechanism in the primary stage of immune defense against microbes.