Abstract
Patients with various types of vasculitis, both nonspecific and that associated with more definitive syndromes such as Henoch Schönlein Purpura (anaphylactoid purpura), have serologic findings which indicate that properdin is consumed during disease activity. In all of 22 patients with documented Henoch Schönlein Purpura, the level of serum properdin was reduced more than three standard deviations below the mean in the first week of the disease. Those patients with predominant signs of abdominal pain and glomerulonephritis had more pronounced reductions in serum properdin than did those with arthritis as a presenting symptom. All other serum C components and alternative pathway proteins including C1–C9, factor B, and factor D were normal. Serum levels of properdin convertase were reduced in 12 of the 22 patients. As the disease subsided, levels of properdin and properdin convertase returned to normal. Properdin has also been found deposited in the glomerulus of these patients by immunofluorescent studies of renal biopsies.
