title: Penetration of antibody-opsonized cells by the membrane attack complex of complement promotes Ca(2+) influx and induces streamers.
abstract: We have reported that during complement-mediated cytolysis of B cells promoted by the CD20 mAbs rituximab or ofatumumab (OFA), long, thin structures that we call streamers (≥ 3 cell diameters) are rapidly generated and grow out from the cell surface. Streamers appear before cells are killed and contain opsonizing mAbs and membrane lipids. By exploiting the differential Ca(2+) requirements of discrete steps in the complement cascade, we determined that mAb-opsonized cells first tagged with C3b using C5-depleted serum are killed on addition of serum and EDTA, but the cells do not produce streamers. Also, cells first opsonized with OFA are lysed in serum containing Mg-EGTA by the alternative complement pathway but streamers are not produced. These findings indicate that Ca(2+) influx is necessary for streamer formation. Other mAbs that promote complement-mediated cytolysis also induce streamers on target cells. Streamer-like structures called nanotubes have been reported in several cellular systems, and are thought to promote intercellular communication/signaling. We tested whether this signaling could influence the susceptibility of neighboring cells contacted by streamers to complement attack and found that complement-mediated cytolysis of OFA-opsonized cells increases the resistance of unopsonized indicator cell populations to subsequent lysis when these cells are exposed to OFA and complement.
authors.affiliation: Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA, USA.
authors.forename: Paul V
authors.initials: PV
authors.lastname: Beum
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Lindorfer
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Peek
authors.forename: P Todd
authors.initials: PT
authors.lastname: Stukenberg
authors.forename: Michel
authors.initials: M
authors.lastname: de Weers
authors.forename: Frank J
authors.initials: FJ
authors.lastname: Beurskens
authors.forename: Paul W H I
authors.initials: PW
authors.lastname: Parren
authors.forename: Jan G J
authors.initials: JG
authors.lastname: van de Winkel
authors.forename: Ronald P
authors.initials: RP
authors.lastname: Taylor
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology*; D061067:Antibodies, Monoclonal, Humanized; D058846:Antibodies, Monoclonal, Murine-Derived / Q000276:immunology; D018951:Antigens, CD20 / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism; D018958:CD55 Antigens / Q000276:immunology / Q000378:metabolism; D002118:Calcium / Q000037:antagonists & inhibitors / Q000276:immunology* / Q000378:metabolism; D002460:Cell Line; D045744:Cell Line, Tumor; D002614:Chelating Agents / Q000494:pharmacology; D003167:Complement Activation / Q000276:immunology; D003179:Complement C3b / Q000276:immunology / Q000378:metabolism; D003182:Complement C5 / Q000276:immunology / Q000378:metabolism; D015938:Complement Membrane Attack Complex / Q000276:immunology* / Q000378:metabolism; D003170:Complement Pathway, Alternative / Q000276:immunology; D003602:Cytotoxicity, Immunologic / Q000187:drug effects / Q000276:immunology*; D004533:Egtazic Acid / Q000494:pharmacology; D005434:Flow Cytometry; D006801:Humans; D017493:Leukocyte Common Antigens / Q000276:immunology / Q000378:metabolism; D008555:Melitten / Q000494:pharmacology; D008856:Microscopy, Fluorescence; D010718:Phosphatidylserines / Q000276:immunology / Q000378:metabolism; D000069283:Rituximab; D044967:Serum / Q000276:immunology / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D058846:Antibodies, Monoclonal, Murine-Derived; D018951:Antigens, CD20; D018958:CD55 Antigens; D002614:Chelating Agents; D003182:Complement C5; D015938:Complement Membrane Attack Complex; D010718:Phosphatidylserines; D008555:Melitten; D000069283:Rituximab; D004533:Egtazic Acid; D003179:Complement C3b; D017493:Leukocyte Common Antigens; C527517:ofatumumab; D002118:Calcium