IgG4 levels were low in this study for only systemic sclerosis and Sjögren's. But other patterns suggested aberrant immune regulation.
Zhang H, Li P, Wu D. Serum IgG Subclasses in Autoimmune Diseases .
Medicine. 2015;94(2):e387 doi: 10.1097/MD.0000000000000387
This study measured the IgG subclasses IgG1, IgG2, IgG3 and IgG4, as absolute values and ratios, in primary SjÃ¶gren syndrome (pSS), systemic sclerosis (SSc), systemic lupus erythematosus (SLE), primary biliary cirrhosis (PBC) and healthy controls using the immunonephelometic assay. They compared the results for all of these groups.
Interestingly, levels of IgG4 were low. However, only 23 (6%) met the criterion for IgG4-related disease (IgG4 >135 mg/dL).
Differences were statistically significant between IgG4 and healthy controls for pSS and SSc, but not for SLE and PBC.
The patterns of IgG1 and IgG3 expression suggested that affected individuals lost tolerance to autoantigens, and also exhibited aberrant immune regulation.
|pSS (n=102)||SSc (n=102)||SLE (n=100)||PBC (n=59)||Controls (n=40)|