Overexpression of B-lymphocyte activating factor (BAFF) results in arthritis, glomerulonephritis and autoantibody formation in mice, but its role in human autoimmune disease is less obvious. Serum BAFF levels in patients with systemic lupus erythematosus (SLE) (n=42) and rheumatoid arthritis (RA) (n=60) were related to levels of disease activity, anti-dsDNA Ab, anti-ENA Ab, rheumatoid factor (RF) and anti-CCP Ab. BAFF levels were also followed over time in 19 SLE patients. BAFF levels correlated inversely with age, were higher in SLE than RA (median 2.7 versus 1.4 ng/mL, P < 0.01) and more SLE than RA patients had increased BAFF levels (57% versus 10%, P < or = 0.01). In SLE, BAFF levels correlated with SLEDAI scores but not with anti-dsDNA Ab levels. SLE patients with increased BAFF levels had higher SLEDAI and CRP levels. In RA, BAFF levels correlated weakly with anti-CCP levels (Rs 0.27, P = 0.07), but not with joint counts, ESR, CRP or RF levels. Longitudinal BAFF levels remained unaltered in two thirds of SLE patients and changes in BAFF levels were unrelated to disease flares. These findings suggest that BAFF stimulation of B-cells may contribute to SLE by other mechanisms than autoantibody production.

Severe lung fibrosis is common in MCTD, has an impact on pulmonary function and overall physical capacity and is associated with increased mortality.

Lower TGF-β1 was the most consistent cytokine abnormality in patients with SLE. The associations with disease activity, lymphocyte subsets, and damage suggest that TGF-β1 may be a therapeutic target of interest in SLE.

The data from the current unselected MCTD cohort suggest that the prevalence of PH is much lower than expected from previous studies but confirm the seriousness of the disease complication.

The underlying mechanisms for the subsets of self-limiting, intermittent or chronic and deforming arthritis in systemic lupus erythematosus (SLE) are not well understood. We performed a cross-sectional analysis of pro-inflammatory cytokines (IL-1β, IL-2, IL-6, IL-8 and TNF-α) and joint status in 47 SLE patients (79% females, age 42 years, disease duration 8.6 years). All cytokines levels were significantly elevated in SLE patients compared with controls, but only IL-2 and IL-8 levels were higher than in patients with rheumatoid arthritis. SLE patients with ongoing synovitis (19%) and joint deformities (11%) had increased erythrocyte sedimentation rate (ESR), IL-6 and anti-dsDNA Ab levels. IL-6 levels correlated with ESR, anti-dsDNA Ab and haemoglobin, but not with C-reactive protein levels. Arthritis constitutes a considerable burden of disease in SLE over time, and joint deformations are associated with longstanding disease and arthritis flare rates. IL-6 is a potential biomarker and therapeutic target in the prevention of joint damage in SLE arthritis.