Primary Sjögren syndrome (pSS) is a systemic autoimmune rheumatic illness affecting the exocrine glands in particular. Dry eye is one of the most common symptoms of this illness, and a recent study found lower deoxyribonuclease I (DNase I) activity in the tears of dry eye patients. As a result, researchers hypothesized that individuals with pSS could have antibodies against DNAse I. In a cross-sectional investigation, they examined 85 patients with pSS, 50 RA patients without sicca symptoms, and 88 healthy volunteers. IgG anti–DNase I antibodies were found using an enzyme-linked immunosorbent test using a bovine pancreatic enzyme as the antigen, and immunoblotting corroborated the results. In all three groups, age and gender were similar. In 43.5 percent of the pSS patients, anti–DNase I was found. All RA patients, on the other hand, lacked this reaction. A further study of pSS patients with and without anti–DNase I revealed that the former had higher IgG serum levels and a higher rate of non–drug-induced leukopenia. Only IgG levels were shown to be independently linked with anti–DNase I antibodies in a multivariate logistic regression study.

They found a significant prevalence of anti–DNase I antibodies in individuals with Parkinson’s disease, which was related to higher blood IgG levels. The absence of reaction in RA patients who do not have sicca symptoms implies that this antibody may be useful in the differential diagnosis of these disorders.