The effect of divalent cations on the rosette formation via C3 receptors.

The indicator cells with the specificity for the various C3 receptors were prepared using highly purified complement components. The effect of EDTA and divalent cations on the rosette formation of these indicators with human blood cells and lymphoblastoid cells were investigated. B lymphocytes form rosettes with EACl-3b, EACl-3bH, EACl-3bi and EACl-3d irrespective of the presence of cations. PMN and monocytes form rosettes with EACl-3b and EACl-3bH independent of cations, but their formation with EAC1-3bi needs the presence of magnesium. In this case calcium shows a cooperative effect with magnesium. PMN and monocytes do not react with EACl-3d even in the presence of magnesium. Although Raji cells do not react with EACl-3b, they react with EACl-3bH independent of divalent cations. EACm has a similar reactivity to EACl-3bi, and by the treatment with trypsin it becomes similar to EACl-3d.