Method: Cross sectional study of patients with established pSS (n= 174), SLE (n=107) and healthy controls (n= 162). FcGr3b CNV was determined by three different RT-PCR parameter estimations (Ct-, Cy0 and CpD1) and confirmed by the Fcgr2c/Fcgr2a paralog ratio test. Clinical and serological data were analyzed for their association with FcGr3b CN.
Result: Low FcGr3b CN was significantly more frequent in SLE (OR 4.15, p=0.003) and pSS (OR 2.67, p=0.013) patients than in controls. In pSS patients, low FcGr3b CN was associated with daytime sleepiness, absence of anti-Ro/La and lower levels of RF and IgG. In contrast, low FcGr3b CN was associated with increased levels of antibodies against dsDNA, C1q and ribosomal P and nephritis in SLE patients. FcGr3b CN did not associate with serum levels of B-cell activating factor in either disease.
Conclusion: Low FcGr3b CN is a susceptibility factor for both pSS and SLE and associates with more severe disease and pathogenic autoantibodies in SLE and extraglandular features in pSS. The contrasting findings for low FCGr3B CN and levels of anti-dsDNA and anti-Ro/La antibodies indicates selective handling of autoantibodies by Fcgr3b on neutrophils in autoimmune diseases.
Disclosure: J. C. Nossent, None; M. Rischmueller, None; A. Becker-Merok, None; S. Lester, None.