Systemic lupus erythematosus (SLE) and Sjögren's syndrome (SS) are systemic autoimmune diseases with complex symptoms and pathogenesis that are still not completely understood. Several studies showed that the trace element homeostasis and also the levels of antioxidant plasma proteins are changed in autoimmune disorders; however, these results are controversial. In this study, the potassium (K), calcium (Ca), magnesium (Mg), copper (Cu), zinc (Zn), and iron (Fe) concentrations of the serum and proteins-immunoglobulin G (IgG), transferrin (Trf), albumin (Alb), and ceruloplasmin (Cp)-separated from serum samples by affinity chromatography were determined in patients with SLE and SS. Ca and K levels were found to be decreased in the case of both disorders compared to the control group, and the competitive antagonism of Cu and Zn was also observed: elevated Cu concentration together with a lower Zn concentration was measured in the sera of patients with autoimmune diseases. After fractionation, the trace element concentration of protein containing fractions altered to that of the control group. In case of the autoimmune disorders, the highest Cu concentration was determined in the Alb-containing protein fractions while the Zn level decreased in the Alb and increased in the Cp as well as in the IgG- and Trf-containing fractions compared to the healthy samples. Changes have also been found in the level and distribution of K and Ca.
Keywords: Blood serum; Elemental analysis; Protein fractionation; Sjögren syndrome; Systemic lupus erythematosus.