Human red cells treated with 20-200 μM diamide were opsonized by serum and phagocytized by adherent monocytes. Phagocytosis was dependent on complement. It was enhanced by supplementing whole serum and was restored by supplementing complement-inactivated serum with naturally occurring antibodies which bind to the major integral protein of the human red cell, band 3 protein. Diamide induced oligomers of anti band 3 reactive oligomers, and enhanced anti band 3 binding to red cells. Complement C3 binding paralleled that of anti band 3 and exceeded it by two orders of magnitude. Thus, naturally occurring antibodies have functional properties which were not abolished by other serum Ig and may be involved together with complement in the clearance of red cells subjected to oxidant stress. Treatment of red cells (RBC) with thiol oxidants (such as diamide, azodicarboxylic acid bisdimethylamide) or thiol alkylators (such as PCMB), at concentrations which do not remarkably affect metabolism (20-200 μM) accelerated RBC removal in vivo. In normal human serum, low amounts of anti band 3 protein antibodies are present. They react with cryptic and exoplasmic domains of band 3 protein, they opsonize senescent or damaged RBC and induce their phagocytosis by adherent monocytes. The present work shows that diamide, used at low concentrations (20-200 μM) induced a mild oxidant stress that enhanced RBC phagocytosis by adherent monocytes, after opsonization with whole serum. The opsonic properties of serum were studied by supplementing whole serum or complement inactivated serum with naturally occurring anti band 3 antibodies. The result suggest an opsonic role for anti band 3 antibody which was abolished by other serum Ig and which was not mimicked by anti spectrin antibodies.
|Journal||Biomedica Biochimica Acta|
|Publication status||Published - 1987|
ASJC Scopus subject areas