The absence of factor B activation products in scleroderma

Previous investigators have reported the presence of complement activation products in scleroderma. Using an assay consisting of isoelectric focussing followed by immunofixation (IEF/IF) for alternative pathway activation product Ba, and an ELISA for C3d that we developed for evaluating lupus plasmas, we assayed 48 plasmas from patients with diffuse cutaneous scleroderma, 16 patients with the limited CREST variant, 2 patients with mixed connective tissue disease (MCTD) and 4 patients with Raynaud's disease. Ba was not detected in any patient's plasma. Only one plasma from a patient with CREST contained elevated levels of C3d. We cannot reconcile the absence of B activation products in our patients with scleroderma with the results of the previous report, and conclude that further studies are necessary.