title: CD59 efficiently protects human NT2-N neurons against complement-mediated damage.
abstract: The complement regulatory protein CD59 controls cell survival by the inhibition of C5b-9 formation on the cell membrane. Loss of CD59 increases the susceptibility of cells to complement-mediated damage and lysis. Deposition of IgM can induce complement activation with subsequent cell death. We have previously demonstrated the presence of CD59 on human NT2-N neurons. In this study, we investigated the functional role of CD59 for NT2-N cell survival after IgM-mediated complement activation. Complement activation was induced on NT2-N neurons with human serum following incubation with the IgM monoclonal antibody A2B5 reacting with a neuronal cell membrane epitope. Deposition of C1q and C5b-9 was detected on the cell membrane and sC5b-9 in the culture supernatant. Specific inhibition of complement was obtained by the C3 inhibitor compstatin, and by anti-C5/C5a MoAb. CD59 was blocked by the MoAb BRIC 229. Membrane damage of propidium iodide-stained NT2-N cells was confirmed by immunofluorescence microscopy and degeneration of neuronal processes was shown with crystal violet staining. A2B5, but not the irrelevant control IgM antibody, induced complement activation on NT2-N neurons after incubation with a human serum, as detected by the deposition of C1q. A marked membrane deposition of C5b-9 on NT2-N neurons with accompanying cell death and axonal degeneration was found after the blocking of CD59 with MoAb BRIC 229 but not with an isotype-matched control antibody. Compstatin and anti-C5 monoclonal antibodies which blocked C5 activation efficiently inhibited complement activation. In conclusion, CD59 is essential for protecting human NT2-N neurons against complement-mediated damage, which is known to occur in a number of clinical conditions including stroke.
authors.affiliation: Institute of Immunology, Rikshospitalet HF, University of Oslo, Oslo, Norway. pedersen@medisin.uio.no
authors.forename: E D
authors.initials: ED
authors.lastname: Pedersen
authors.forename: H C D
authors.initials: HC
authors.lastname: Aass
authors.forename: T
authors.initials: T
authors.lastname: Rootwelt
authors.forename: M
authors.initials: M
authors.lastname: Fung
authors.forename: J D
authors.initials: JD
authors.lastname: Lambris
authors.forename: T E
authors.initials: TE
authors.lastname: Mollnes
mesh_terms: D018957:CD59 Antigens / Q000502:physiology*; D016923:Cell Death / Q000276:immunology; D045744:Cell Line, Tumor; D002474:Cell-Free System; D003167:Complement Activation / Q000276:immunology*; D015938:Complement Membrane Attack Complex / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D007075:Immunoglobulin M / Q000502:physiology; D009474:Neurons / Q000276:immunology* / Q000378:metabolism / Q000473:pathology
chemical_list: D018957:CD59 Antigens; D015938:Complement Membrane Attack Complex; D007075:Immunoglobulin M; C051590:CD59 protein, human