Background/Purpose:  Autoantibodies in SLE that bind to double-stranded DNA or RNA-binding proteins are strongly associated with high levels of type I interferon (IFN), likely via their ability these antibodies to form nucleic-acid containing immune complexes that can stimulate Toll-like receptors. In this study, we examine whether anti-phospholipid antibodies, which should not have this capacity, are associated with greater type I interferon in SLE patients.

Methods:   We studied 392 SLE patients (223 African-American, 101 European-American, and 68 Hispanic-American ancestry) and measured type I IFN in sera. Antiphospholipid (APL), anti-RBP, and anti-dsDNA antibodies were measured in the clinical laboratory, and standard clinical cut-offs were used to define a positive result. Non-parametric analyses were used to compare IFN data with the antibody data in each ancestral background.

Results:   African-American subjects with a positive IgG APL antibody test had higher type I IFN levels than those without APL antibodies (p=0.02). This was not observed in the other ancestral backgrounds, and in fact the opposite trend was observed in Hispanic-Americans. African-Americans were less likely to have a positive IgG APL test than European-Americans (p=0.0067, OR=2.3), and those African-Americans with a positive IgG APL test were more likely to also have anti-dsDNA antibodies (p=0.04, OR=2.5).

Conclusion:   These data suggest a distinct serological profile in African-American patients, in which a positive APL antibody test corresponds with a significantly greater type I IFN level and more frequent anti-dsDNA antibodies, and this is not shared with other ancestral backgrounds. These data support differences in the molecular pathogenesis of SLE by ancestral background that may impact treatment strategies.

« Back to 2016 ACR/ARHP Annual Meeting

ACR Meeting Abstracts - https://acrabstracts.org/abstract/associations-between-type-i-interferon-and-antiphospholipid-antibody-status-differ-between-ancestral-backgrounds/