Serum antibody reactivity to human intracisternal A-type particle retrovirus proteins in systemic sclerosis patients.

Serum antibodies against human intracisternal A-typeparticle (HIAP) endogenous retrovirus have been foundto be associated with various autoimmune pathologies.To evaluate the presence of serum antibody reactivityto HIAP proteins in systemic sclerosis, a Western blotanalysis was performed on sera from 42 patients withsystemic sclerosis, in comparison with 18 sera frompatients with primary biliary cirrhosis and 52 healthysubjects. A positive Western blot was found in 55.5% ofserum samples from patients with primary biliarycirrhosis and in 66.0% of patients with systemic sclerosis.None of the 52 healthy subjects showed positive results.Although this difference may be attributable either to anautoimmune response to antigenically related cellularproteins or to a specific antibody response to HIAPproteins expressed as an incidental consequence ofattendant pathological processes, the high prevalence ofantibodies against HIAP proteins demonstrated inpatients with systemic sclerosis may be considered ahallmark of this disease.(Accepted November 10, 2003.)Acta Derm Venereol 2004; 84: 177–180.Dr Michelangelo La Placa, Department of Clinicaland Experimental Medicine, Section of Dermatology,Via Massarenti, 1, 40138 Bologna, Italy. E-mail:[email protected] sclerosis (SSc) is a connective tissue diseasecharacterized by excessive deposition of collagen inthe skin and various internal organs, and by vascularabnormalities (1). SSc is considered to be an auto-immune disease. Although both cellular microchimer-ism (2) and molecular mimicry of some commoninfectious agents, such as cytomegalovirus and parvo-virus B19 (3), have been implicated in its pathogenesis,the aetiology of SSc remains unknown.Several publications have described the presence ofretroviral sequences associated with virions, producedby cells of patients with autoimmune diseases. In recentreviews (4, 5), these viruses, identified as human endo-genous retroviruses (HERVs), have been associatedwith Sjo¨grens's syndrome, type 1 or insulin-dependentdiabetes mellitus, multiple sclerosis, rheumatoid arthri-tis, congenital heart block, systemic lupus erythemato-sus and SSc. Serum antibodies specific for humanintracisternal A-type particles (HIAP), a HERV recog-nized by monoclonal antibody against HIV-1 p24capsid protein (6), have been found in primary biliarycirrhosis (PBC) (7), familial erosive arthritis (8) andsome patients with SSc, systemic lupus erythematosus,Still's disease and idiopathic T-lymphocytopenia (9,10).To further investigate serum antibody reactivity toHIAP proteins in SSc, we performed a Western blotanalysis of a substantial number of sera from SScpatients, in comparison with sera from PBC patientsand healthy subjects.MATERIALS AND METHOD