Sjögren's syndrome in inflammatory rheumatic diseases: analysis of the leukocyte protein calprotectin in plasma and saliva.

In a hospital population of 154 patients with a wide range of inflammatory rheumatic diseases, patients with sicca symptoms were subjected to objective ocular and oral tests to establish cases with Sjögren's syndrome (SS). The plasma level of the leukocyte protein calprotectin has been shown to be a good indicator of disease activity and inflammation in various rheumatic diseases. In the present study, calprotectin levels in plasma and whole saliva were analysed and evaluated as potential markers of SS and salivary gland disease activity. Plasma calprotectin levels did not differ significantly between patients with SS and patients with no sicca symptoms. However, salivary calprotectin levels correlated significantly with the plasma calprotectin levels and with several ocular variables, weakly with salivary flow and serum rheumatoid factor, but not with focal sialadenitis. In conclusion, this study shows that salivary calprotectin levels seem to be associated with several variables of SS glandular pathology, indicating the need for further and more comprehensive studies on calprotectin in various oral fluids and in lacrimal fluid in relation to SS glandular disease activity.