title: Evaluation of in vivo immune complex formation and complement activation in patients receiving intravenous streptokinase.
abstract: The usefulness of several different methods for detecting immune complex formation and complement activation in the circulation were applied to samples from patients receiving intravenous Streptokinase therapy for myocardial infarction. Streptokinase is a foreign antigen and can cause immune reactions. We collected samples from 13 patients, before Streptokinase administration (baseline), at the end of infusion (1 h), 12 h later and on day 7. We measured IgG containing immune complexes (IgG-IC), free C3d and antibodies to Streptokinase by ELISA, and CR1, C3d and C4d on erythrocytes by flow cytometric assay. Antibodies to Streptokinase are common, as all but two of the patients had measurable antibody levels. During Streptokinase treatment there was a drop in antibody levels, most prominent in those patients who had high baseline levels. At the same time increased levels of free C3d and erythrocyte-bound C3d were observed. After 12 h free C3d was usually back to baseline level, but C3d on erythrocytes was still raised. These data indicate the formation of Streptokinase immune complexes in patients with high Streptokinase antibody levels, and show that these complexes are cleared rapidly from the circulation, leaving more persistent signs of complement activation. We conclude that free C3d is a good indicator of ongoing complement activation, whereas C3d on erythrocytes indicates that complement activation has recently taken place.
authors.affiliation: Department of Immunology, National University Hospital, Reykjavik, Iceland.
authors.forename: J
authors.initials: J
authors.lastname: Freysdottir
authors.forename: S
authors.initials: S
authors.lastname: Ormarsdottir
authors.forename: A
authors.initials: A
authors.lastname: Sigfusson
mesh_terms: D000906:Antibodies / Q000097:blood; D000936:Antigen-Antibody Complex / Q000096:biosynthesis*; D003167:Complement Activation / Q000187:drug effects*; D003176:Complement C3 / Q000378:metabolism; D015933:Complement C3d / Q000378:metabolism; D003181:Complement C4 / Q000378:metabolism; D015935:Complement C4b; D004912:Erythrocytes / Q000276:immunology; D006801:Humans; D007262:Infusions, Intravenous; D009203:Myocardial Infarction / Q000188:drug therapy; D010446:Peptide Fragments / Q000378:metabolism; D017463:Receptors, Complement 3b / Q000378:metabolism; D013300:Streptokinase / Q000008:administration & dosage / Q000009:adverse effects* / Q000276:immunology
chemical_list: D000906:Antibodies; D000936:Antigen-Antibody Complex; D003176:Complement C3; D003181:Complement C4; D010446:Peptide Fragments; D017463:Receptors, Complement 3b; D015933:Complement C3d; D015935:Complement C4b; C032261:complement C4d; D013300:Streptokinase