Studies of Mopc 104E Plasmacytoma Cells Forming Rosettes with Autologous and Syngeneic Erythrocytes¹

MOPC 104E plasmacytoma cells secreting an IgM antibody to dextran 1355 S1,3 were shown to make mixed rosettes with both dextran-coated chicken erythrocytes (D-CRBC) and syngeneic mouse erythrocytes from tumor-bearing mice (T-MRBC). D-CRBC rosettes were readily blocked by soluble dextran, monospecific goat anti-mouse IgM, anti-mouse IgG₂ but not anti-mouse IgG₁. T-MRBC rosettes were blocked by monospecific anti-mouse IgG₂, but not with anti-mouse IgM or soluble dextran. These results indicate that the plasmacytoma carries an IgG₂-like receptor to T-MRBC.