PTX3 in small-vessel vasculitides: an independent indicator of disease activity produced at sites of inflammation.

To verify whether the prototypical long pentraxin PTX3 represents an indicator of the activity of small-vessel vasculitis. Concentrations of PTX3, a pentraxin induced in endothelium by cytokines, were measured by enzyme-linked immunosorbent assay in the sera of 43 patients with Churg-Strauss syndrome, Wegener's granulomatosis, and microscopic polyangiitis. PTX3 was also measured in the sera of 28 patients with systemic lupus erythematosus (SLE), 22 with rheumatoid arthritis, and 16 with CREST syndrome (calcinosis, Raynaud's phenomenon, esophageal dysmotility, sclerodactyly, telangiectasias). Serum concentrations of C-reactive protein (CRP) were measured by immunoturbidimetry. The cells involved in PTX3 production in vivo were identified in skin biopsy samples. Patients with active vasculitis had significantly higher concentrations of PTX3 than did those with quiescent disease (P < 0.001). PTX3 levels in the latter group were similar to those in healthy controls. PTX3 levels were higher in patients with untreated vasculitis and lower in patients who underwent immunosuppressive treatments (P < 0.005). In contrast, patients with active SLE had negligible levels of the pentraxin. PTX3 levels did not correlate with CRP levels in vasculitis patients. Endothelial cells produced PTX3 in active skin lesions. PTX3 represents a novel acute-phase reactant produced at sites of active vasculitis.