A novel Fc receptor for IgA and IgM is expressed on both hematopoietic and non‐hematopoietic tissues

• Published in: European journal of immunology Vol. 31; no. 5; pp. 1310 - 1316
• Main Authors: Sakamoto, Norihisa, Shibuya, Kazuko, Shimizu, Yoshio, Yotsumoto, Katsumi, Miyabayashi, Tomoyuki, Sakano, Seiji, Tsuji, Takao, Nakayama, Eiichi, Nakauchi, Hiromitsu, Shibuya, Akira
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY‐VCH Verlag GmbH 01.05.2001
• Subjects: AFc receptors; Animals; B lymphocyte; B-Lymphocytes - cytology; B-Lymphocytes - immunology; B-Lymphocytes - metabolism; Bone Marrow Cells - immunology; Bone Marrow Cells - metabolism; Cell Line; Endocytosis - drug effects; Fc receptor; Fcα/μ receptor; Flow Cytometry; Humans; IgM; Immunoglobulin A - immunology; Immunoglobulin M - immunology; Kidney,intestine; Mice; Microspheres; phorbol 12-myristate 13-acetate; Receptors, Fc - immunology; Receptors, Fc - metabolism; RNA, Messenger - analysis; RNA, Messenger - genetics; Spleen - cytology; Spleen - immunology; Tetradecanoylphorbol Acetate - pharmacology; Transfection
• ISSN: 0014-2980; 1521-4141
• DOI: 10.1002/1521-4141(200105)31:5<1310::AID-IMMU1310>3.0.CO;2-N

By contrast to well‐defined Fcγ and Fcϵ receptors, the structural and functional characteristics of Fcμ receptor are unclear. We have recently described a novel mouse Fc receptor, designated Fcα/μ receptor, and its human homologue, which bind both IgM and IgA. Here we show that the Fcα/μ receptor is expressed on mature, but not immature, B lymphocytes and acquires the ability to bind IgM and IgA antibodies after stimulation of B lymphocytes. Moreover, stimulation with phorbol 12‐myristate 13‐acetate increased endocytosis of IgM‐coated microparticles mediated by the Fcα/μ receptor expressed on pro‐B cell line Ba/F3 cells. We also show that the Fcα/μ receptor is expressed in secondary lymphoid organs, such as lymph node and appendix, kidney and intestine, suggesting an important role of the receptor for immunity in these organs.