Immune complex alterations occur on the human red blood cell membrane.
Experimental antigen-antibody complexes (Ag-Ab) were incubated at 37 degrees with human red blood cells (RBC) suspended in autologous normal serum and the reaction stopped after progressively increasing times. Bound antigen-antibody-complement complexes (Ag-Ab-C) were eluted from C3b receptors and the eluted Ag-Ab-C re-incubated with different blood cell types suspended in serum, or centrifuged (along with unbound Ag-Ab-C found in the serum) through 20-50% sucrose gradients. Ag-Ab-C recovered from C3b receptors shortly after initial binding to RBC bound efficiently to other RBC, polymorphonuclear and mononuclear cells, and sedimented rapidly. Ag-Ab-C simultaneously present in the serum sedimented with a similar velocity. Ag-Ab-C recovered at a subsequent time during RBC interaction bound less well to each blood cell type, and sedimented less rapidly. Decreased amounts of rapidly sedimenting Ag-Ab-C were present in the serum. Ag-Ab-C recovered from C3b receptors at a still later time in the course of RBC interaction bound poorly to each cell type, and sedimented slowly. Increased amounts of slowly sedimenting Ag-Ab-C were found in the serum. These findings indicate that alterations in properties of immune complexes can occur while they are associated with C3b receptors on RBC membrane in solid phase.
D000936:Antigen-Antibody Complex / Q000378:metabolism*; D004910:Erythrocyte Membrane / Q000276:immunology*; D004912:Erythrocytes / Q000276:immunology*; D006801:Humans; D007700:Kinetics; D007962:Leukocytes / Q000276:immunology; D009504:Neutrophils / Q000276:immunology; D011951:Receptors, Complement / Q000378:metabolism; D017463:Receptors, Complement 3b; D014461:Ultracentrifugation
D000936:Antigen-Antibody Complex; D011951:Receptors, Complement; D017463:Receptors, Complement 3b