Longitudinal study of interleukin-10, tumor necrosis factor- α, anti-U1-snRNP antibody levels and disease activity in patients with mixed connective tissue disease

Abstract

Objective. To investigate the levels and relationship between IL-10, TNF- f, anti-U1snRNP antibodies and disease activity in longitudinally collected serum samples from patients with mixed connective tissue disease (MCTD). Methods. Six patients followed for 17-138 months were investigated with ELISA for estimation of cytokine levels and antibodies to the different epitopes of the U1snRNP. Disease activity was assessed by systemic lupus activity measure (SLAM). Results. IL-10 and TNF- f levels fluctuated with time in at least half of the patients. Three patients had increased IL-10 levels and two had increased TNF- f in all samples. There was no correlation between cytokine levels and disease activity or clinical manifestations. All patients had increased levels of antibodies to the main components of the U1snRNP. Both antibody levels and disease activity decreased with time. A correlation between TNF-alpha and U1snRNP antibody levels were observed in five patients. Conclusions. Increased and fluctuating levels of IL-10 or TNF- f without correlation to disease activity were observed in MCTD patients. In some patients increased cytokine levels were observed over several years irrespective of disease activity indicating that they could be constitutively increased in these individuals.