Complement-activating abilities of defined antinuclear antibodies.
A complement-fixing immunofluorescence assay on HEp-2 cells was used to assess the ability of various antinuclear antibodies (ANA) to activate complement. Sera which contained only specific antibodies to nuclear RNP, SS-B/La, centromere, Sm antigen, double-stranded DNA, and/or nuclear histone were selected. Relative abilities of various ANA to activate complement were determined from the ratio of titers of C3, C4, or properdin-fixing ANA to the IgG ANA titers. Nuclear RNP-anti-RNP complexes activated and deposited significantly more complement C3 than other ANA (P less than 0.02). Antibodies to SS-B/La, centromere, and Sm activated more complement than anti-DNA or antihistone (P less than 0.02). Antihistone antibodies activated the least complement. These studies demonstrate that different ANA have significantly different orders of complement-activating capabilities when bound to their respective nuclear antigens.
D000974:Antibodies, Antinuclear / Q000032:analysis / Q000502:physiology*; D001324:Autoantigens / Q000032:analysis; D002503:Centromere / Q000276:immunology; D003095:Collagen Diseases / Q000276:immunology*; D003167:Complement Activation; D003176:Complement C3 / Q000276:immunology; D003181:Complement C4 / Q000276:immunology; D003168:Complement Fixation Tests; D004247:DNA / Q000276:immunology; D006657:Histones / Q000276:immunology; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology; D011414:Properdin / Q000276:immunology; D012261:Ribonucleoproteins / Q000276:immunology; D017411:Ribonucleoproteins, Small Nuclear; D055517:snRNP Core Proteins
D000974:Antibodies, Antinuclear; D001324:Autoantigens; D003176:Complement C3; D003181:Complement C4; D006657:Histones; D007074:Immunoglobulin G; D012261:Ribonucleoproteins; D017411:Ribonucleoproteins, Small Nuclear; C035357:SS-B antibodies; D055517:snRNP Core Proteins; D011414:Properdin; D004247:DNA