404 Anti-phosphatidylserine/prothrombin complex antibodies in patients with cutaneous vasculitis: Possible involvement in the pathogenesis

Abstract

Objective. It was previously demonstrated that cutaneous vasculitis, including IgA vasculitis and cutaneous arteritis (CA), is associated with the presence of IgM antibodies (Abs) against the phosphatidylserine/prothrombin complex (PS/PT). Recently, novel enzyme-linked immunosorbent assay kits for the detection of IgG and IgM anti-PS/PT (aPS/PT) Abs have become commercially available.Methods. The prevalence of serum IgG and IgM aPS/PT Abs in both cutaneous and systemic vasculitis was determined using these kits. In addition, to examine whether aPS/PT Abs were involved in the pathogenesis of cutaneous vasculitis, inbred wild-type rats were intravenously administered with a rat IgM class aPS/PT monoclonal Ab established previously or with rat immunoglobulins as controls. To express PS on the surface of vascular endothelium, these rats were given a subcutaneous injection of cell-free histones (250 µg/ml, 300 µl/site) 2 hours in advance.Results. Serum IgM aPS/PT Ab levels were elevated in patients with systemic vasculitis with skin involvement and CA compared to those in patients with systemic vasculitis without skin involvement and healthy controls. There was no signi cant difference in the serum levels of IgG aPS/PT Abs between the patients and healthy controls. Correspondingly, inbred wild-type rats intravenously administered with the aPS/PT monoclonal IgM Ab after appropriate priming-subcutaneous histone injection-developed cutaneous vasculitis. Some rats given rat IgM instead of the aPS/PT monoclonal Ab also developed cutaneous vasculitis, whereas vasculitis did not occur in rats given IgG or only priming by histones. Conclusion.IgM aPS/PT Abs could be involved in the pathogenesis of cutaneous vasculitis.