title: Concomitance of IgM and IgG anti-dsDNA Antibodies Does Not Appear to Associate to Active Lupus Nephritis.
abstract: Previous reports proposed that the IgM anti-dsDNA antibody is protective for lupus nephritis. In this cross-sectional study, we aimed to compare clinical features of systemic lupus erythematosus (SLE) patients positive for IgG anti-dsDNA alone with those presenting both IgG and IgM anti-dsDNA. Anti-dsDNA antibodies, urinary examination and complement levels were assessed in the day of appointment. IgG and IgM anti-dsDNA antibodies were detected by indirect immunofluorescence. Fifty-eight SLE patients (93.1% female, 81% European-derived, mean age 42.8±14.7 years, mean duration of disease 10.9±8 years) positive for IgG anti-dsDNA entered the study. Of those, 15 were also positive for the IgM anti-dsDNA isotype. The group with both isotypes showed significant less frequency of active nephritis (sediment changes and proteinuria) when compared to patients with IgG anti-dsDNA alone (6.7% versus 34.9%, p=0.046). These data suggest a nephroprotective role for IgM anti-dsDNA and a distinct biologic behavior for this isotype in SLE.
authors.affiliation: Department of Rheumatology, Hospital São Lucas, Pontifícia Universidade Católica do Rio Grande do Sul - PUCRS., Brazil.
authors.forename: Briele
authors.initials: B
authors.lastname: Keiserman
authors.affiliation: Department of Rheumatology, Hospital São Lucas, Pontifícia Universidade Católica do Rio Grande do Sul - PUCRS., Brazil.
authors.forename: Maria Rita
authors.initials: MR
authors.lastname: Ronchetti
authors.affiliation: Department of Rheumatology, Hospital São Lucas, Pontifícia Universidade Católica do Rio Grande do Sul - PUCRS., Brazil.
authors.forename: Odirlei Andre
authors.initials: OA
authors.lastname: Monticielo
authors.affiliation: Department of Rheumatology, Hospital São Lucas, Pontifícia Universidade Católica do Rio Grande do Sul - PUCRS., Brazil.
authors.forename: Mauro Waldemar
authors.initials: MW
authors.lastname: Keiserman
authors.affiliation: Department of Rheumatology, Hospital São Lucas, Pontifícia Universidade Católica do Rio Grande do Sul - PUCRS., Brazil.
authors.forename: Henrique Luiz
authors.initials: HL
authors.lastname: Staub
keywords: IgG and IgM anti-dsDNA antibodies.; Systemic lupus erythematosus; lupus nephritis