Seventeen human monoclonal IgGl‐ 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 IgGl 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‐γ increased the percentage of cells forming rosettes with IgG3‐ and IgGl‐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/IgGl than FcRI/IgG3 interactions are required.
|Number of pages||7|
|Publication status||Published - Nov 1988|
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