FcalphaRI-positive liver Kupffer cells: reappraisal of the function of immunoglobulin A in immunity.
Despite the well-recognized involvement of immunoglobulin (Ig) A in mucosal immunity, the function of its receptor, FcalphaRI (CD89), is poorly understood. The ability of FcalphaRI to activate leukocytes seems to conflict with the proposed anti-inflammatory activity of secretory IgA. We show here that in a transgenic mouse model, inflammatory mediators induced expression of FcalphaRI on Kupffer cells, which enabled efficient phagocytosis in vivo of bacteria coated with serum IgA. Secretory IgA did not initiate phagocytosis. Therefore, interactions between serum IgA and FcalphaRI on Kupffer cells may provide a 'second line of defense' in mucosal immunity, by eliminating invasive bacteria entering through the portal circulation and thus preventing disease.
van Egmond
M
M
Department of Immunology and Medarex Europe, University Medical Center Utrecht, Lundlaan 6, 3584 EA Utrecht, The Netherlands.
van Garderen
E
E
van Spriel
A B
AB
Damen
C A
CA
van Amersfoort
E S
ES
van Zandbergen
G
G
van Hattum
J
J
Kuiper
J
J
van de Winkel
J G
JG
D000818:Animals; D015703:Antigens, CD / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D004926:Escherichia coli / Q000276:immunology; D015870:Gene Expression; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood / Q000276:immunology*; D007071:Immunoglobulin A, Secretory / Q000276:immunology; D007728:Kupffer Cells / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology; D008099:Liver / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008822:Mice, Transgenic; D010587:Phagocytosis / Q000276:immunology; D011961:Receptors, Fc / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*
D015703:Antigens, CD; C036832:Fc(alpha) receptor; D007070:Immunoglobulin A; D007071:Immunoglobulin A, Secretory; D011961:Receptors, Fc