Non-specific binding of IgG to antibody-coated red cells. (The 'Matuhasi-Ogata phenomenon').

Several observers have reported that red cells coated with a specific blood-group antibody may take up a second blood-group antibody non-specifically, an effect known as the `Matuhasi—Ogata phenomenon'. In the present work, this effect was investigated using either I-labelled antibodies of various specificities or a I-labelled preparation of IgG lacking relevant antibodies. In confirmation of much previous work, it was found that red cells took up appreciable amounts of IgG non-specifically; however, this uptake was not increased by previous coating of the red cells with specific antibody. When the IgG taken up non-specifically included a blood-group antibody in relatively high concentration, an eluate subsequently prepared from the red cells contained sufficient of the antibody to be detectable. Thus, the finding of unexpected antibodies in eluates may be due to non-specific uptake of IgG rather than to adherence of antibodies to antigen—antibody complexes.