Blocking antibodies specific for human albumin interfere with the hemolytic activity of the membrane attack complex of complement.
Earlier, we showed that antibodies specific for human serum albumin are able to bind to erythrocyte-associated albumin and inhibit complement mediated hemolysis. In the present study we determine if inhibition is occurring at the membrane attack phase of complement activation or at an earlier step. We show that although cell-bound anti-albumin antibodies do not inhibit binding and activation of C3 or uptake of C9, they do appear to cause cells to become refractory to lysis by the membrane attack complex as they inhibit both the kinetics and the extent of hemolysis in a reactive lysis system which employs preformed C5b6 plus C7, C8, and C9. We believe that this is the first report of inhibition of the hemolytic activity of the membrane attack complex by antibodies bound to an erythrocyte surface antigen.
Houle
J J
JJ
Department of Microbiology and Cell Science, University of Florida, Gainesville 32611-0330.
Hoffmann
E M
EM
D000818:Animals; D000906:Antibodies / Q000097:blood / Q000494:pharmacology*; D000918:Antibody Specificity; D002003:Brucella abortus; D003185:Complement C8 / Q000378:metabolism; D003186:Complement C9 / Q000378:metabolism; D015938:Complement Membrane Attack Complex / Q000187:drug effects / Q000378:metabolism*; D004912:Erythrocytes / Q000187:drug effects / Q000502:physiology; D006041:Goats / Q000276:immunology; D006461:Hemolysis / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D007700:Kinetics; D008070:Lipopolysaccharides / Q000494:pharmacology; D010446:Peptide Fragments / Q000302:isolation & purification / Q000378:metabolism; D012709:Serum Albumin / Q000276:immunology*
D000906:Antibodies; D003185:Complement C8; D003186:Complement C9; D015938:Complement Membrane Attack Complex; D008070:Lipopolysaccharides; D010446:Peptide Fragments; D012709:Serum Albumin