Plasma levels of soluble interleukin 2 receptor, soluble CD30, interleukin 10 and B cell activator of the tumour necrosis factor family during follow-up in vasculitis associated with proteinase 3-antineutrophil cytoplasmic antibodies: associations with disease activity and relapse.

OBJECTIVES: To evaluate whether T cell activation, as reflected by levels of soluble interleukin 2 receptor (sIL2R), soluble CD30 (sCD30), IL-10 and B cell activator of the tumour necrosis factor family (BAFF) at diagnosis and during initial follow-up, is predictive for persistent or renewed antineutrophil cytoplasmic antibody (ANCA) positivity and clinical relapse in patients with vasculitis associated with proteinase 3-antineutrophil cytoplasmic antibodies (PR3-ANCA).
METHODS: 87 Patients with PR3-ANCA-associated vasculitis and at least 2 years of follow-up were included in the study. At diagnosis, and at 3, 6, 12, 18 and 24 months after diagnosis, cytoplasmic ANCA titres were detected by indirect immunofluorescence (IIF), and PR3-ANCA, sIL2R, sCD30, IL-10 and BAFF levels were assessed by ELISA. 31 healthy volunteers provided plasma samples for comparison. Levels of immune markers were related to ANCA positivity and relapse during follow-up.
RESULTS: Plasma levels of sIL2R, sCD30 and BAFF were higher in patients than in controls at all time points. Plasma levels of sIL2R, sCD30 and IL-10 were higher at diagnosis and relapse than during remission. At 18 months, sCD30 (p<0.001) and sIL2R levels (p = 0.01) were significantly higher in PR3-ANCA-positive patients (detected by ELISA) than in PR3-ANCA-negative patients. ANCA-positive patients detected by ELISA or IIF at 24 months had significantly higher plasma sCD30 levels (p = 0.02 and p = 0.03, respectively) than ANCA-negative patients.
CONCLUSION: Increased T cell activation in patients with ANCA-associated vasculitis in remission during and after immunosuppressive treatment is associated with persistent or renewed ANCA positivity.