Unusual biochemical features and follicular dendritic cell expression of human Fcalpha/mu receptor.
The Fc receptor for IgA and IgM (Fcalpha/muR) is of particular interest because it can bind antibodies of both IgM and IgA isotypes and thus may play a pivotal role in systemic and mucosal immunity. Using IgM and IgA ligands and newly generated Fcalpha/muR specific monoclonal antibodies we have defined biochemical features and cellular distribution of the human Fcalpha/muR. Both recombinant and native forms of human Fcalpha/muR are expressed on the cell surface as remarkably stable homodimeric transmembrane glycoproteins that can bind specifically polymeric IgM or IgA. The only human B cells to express Fcalpha/muR, albeit at very low levels, are found in the pre-germinal center subpopulation defined by the IgD+/CD38+ phenotype. Hence the expression pattern differs from that of the mouse wherein Fcalpha/muR is expressed by both circulating and resident B cell populations. Significantly, the predominant cell type expressing the Fcalpha/muR in humans is the follicular dendritic cell of germinal centers. The Fcalpha/muR may thus function in antigen presentation and B cell selection in the germinal center response.
Kikuno
Kaoru
K
Department of Pathology, University of Alabama at Birmingham, Birmingham 35294-2182, USA.
Kang
Dong-Won
DW
Tahara
Kazuki
K
Torii
Ikuko
I
Kubagawa
Homare M
HM
Ho
Kang Jey
KJ
Baudino
Lucie
L
Nishizaki
Naoto
N
Shibuya
Akira
A
Kubagawa
Hiromi
H
D000328:Adult; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D016175:B-Lymphocyte Subsets / Q000378:metabolism; D001854:Bone Marrow Cells / Q000378:metabolism; D045744:Cell Line, Tumor / Q000378:metabolism; D020566:Dendritic Cells, Follicular / Q000378:metabolism*; D019281:Dimerization; D005786:Gene Expression Regulation; D018858:Germinal Center / Q000166:cytology*; D006801:Humans; D007070:Immunoglobulin A / Q000378:metabolism; D007075:Immunoglobulin M / Q000378:metabolism; D008221:Lymphoid Tissue / Q000378:metabolism; D016399:Lymphoma, T-Cell / Q000473:pathology; D051379:Mice; D009928:Organ Specificity; D014066:Palatine Tonsil / Q000166:cytology / Q000378:metabolism; D010954:Plasmacytoma / Q000473:pathology; D054448:Precursor Cells, B-Lymphoid / Q000378:metabolism; D011961:Receptors, Fc / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013154:Spleen / Q000166:cytology / Q000378:metabolism
D000911:Antibodies, Monoclonal; C526791:Fcalpha-mu protein, mouse; C526790:Fcalpha-mu receptor, human; D007070:Immunoglobulin A; D007075:Immunoglobulin M; D011961:Receptors, Fc; D011993:Recombinant Fusion Proteins; C034639:polymeric IgA; C024242:polymeric IgM