Cytokine production, serum levels and disease activity in systemic lupus erythematosus

Objective T cell abnormalities, B cell hyperactivity and abnormal cytokine production have been implicated to be of pathogenic importance in systemic lupus eryt hematosus (SLE). The aim of this study was to investigate if ongoing produc tion and serum levels of type 1 and 2 cytokines reflect disease activity an d the presence of organ manifestations. Methods Fifty-two SLE patients and 29 healthy individuals were investigated. Blood samples were collected for assessment of anti-ds DNA antibodies, cytokine p roduction and serum cytokine levels. Disease activity was simultaneously as sessed using the Systemic Lupus Activity Measure (SLAM) index and SLE Disea se Activity Index (SLEDAI). ELISPOT analysis of freshly isolated peripheral blood mononuclear cells (PBMC) was used to estimate the production of cyto kines (gamma-interferon (IFN-gamma), interleukin-4 (IL-4), IL-6 and IL-10) using both unstimulated cells and cells stimulated with the T cell mitogen phytohaemagglutinin (PHA). Serum levels of IL-10 were determined using an E LISA method, serum levels of IL-6 were determined using a bioassay and anti -dr DNA antibodies were analysed by immunofluorescence. Results The SLE patient group had significantly increased numbers of cells spontane ously producing IL-10 and IL-6 as compared to healthy controls (P = 0.01 an d 0.03, respectively). The number of cells producing IL-10 and IL-6 after P HA-stimulation was also increased in SLE patients (P = 0.01 and < 0.0004, r espectively). Serum IL-10 and IL-6 levels were also significantly increased in SLE patients (P < 0.0004 and 0.0005, respectively). Serum IL-10 levels correlated with the titre of anti-ds DNA antibodies in the patients. No cor relation was found between disease activity or clinical profiles and the pr oduction or serum levels of cytokines except for a weak correlation (not st atistically significant) between levels of IL-10 in the sera and disease ac tivity as measured by the SLEDAI but not by the SLAM index. Conclusion Our results confirm earlier reports that. SLE patients have an increased pr oduction as well as increased serum levels of the type 2 cytokines IL-10 an d IL-6. We found no significant correlation between IL-6 and IL-10 and dise ase activity or clinical profiles. Serum IL-10 levels correlated with the t itre of anti-ds DNA antibodies in the SLE patients. In summary our result i ndicate that the increased IL-10 production in SLE could be constitutive.