Immunogenic and antigenic epitopes of immunoglobulins binding of human monoclonal anti-D antibodies to FcRI on the monocyte-like U937 cell line.
Seventeen human monoclonal IgG1- or IgG3 anti-D-secreting clones have been examined for their ability to sensitise O+ red cells for Fc-receptor-mediated rosette formation with U937 cells. IgG3 but not IgG1 anti-D antibodies were able to mediate stable rosette formation with unstimulated U937 cells via interaction with the FcRI receptor. Decreasing FcRI density by incubating U937 cells with di-butyryl cAMP almost completely abolished rosette formation, whilst increasing FcRI density by incubating U937 cells with interferon-gamma increased the percentage of cells forming rosettes with IgG3- and IgG1-sensitised red cells. These data suggest that rosette formation between IgG anti-D-sensitised red cells and FcRI-expressing cells is dependent upon the density of IgG3 on the red cell surface, the density of FcRI on the effector cell, multiple FcRI/IgG interactions are required for stable rosette formation and that more FcRI/IgG1 than FcRI/IgG3 interactions are required.
Walker
M R
MR
Department of Immunology, Medical School, Birmingham, UK.
Kumpel
B M
BM
Thompson
K
K
Woof
J M
JM
Burton
D R
DR
Jefferis
R
R
D001666:Binding Sites, Antibody; D002460:Cell Line; D000939:Epitopes / Q000276:immunology*; D004912:Erythrocytes / Q000276:immunology; D006386:Hemagglutination Tests; D006801:Humans; D007141:Immunoglobulin Fc Fragments / Q000276:immunology*; D007074:Immunoglobulin G / Q000276:immunology*; D009000:Monocytes / Q000276:immunology; D012204:Rh-Hr Blood-Group System / Q000276:immunology*; D012397:Rosette Formation
D000939:Epitopes; D007141:Immunoglobulin Fc Fragments; D007074:Immunoglobulin G; D012204:Rh-Hr Blood-Group System