Serum Antibody Reactivity to Human Intracisternal A-Type Particle Retrovirus Proteins in Systemic Sclerosis Patients

Serum antibodies against human intracisternal A-type particle (HIAP) endogenous retrovirus have been found to be associated with various autoimmune pathologies. To evaluate the presence of serum antibody reactivity to HIAP proteins in systemic sclerosis, a Western blot analysis was performed on sera from 42 patients with systemic sclerosis, in comparison with 18 sera from patients with primary biliary cirrhosis and 52 healthy subjects. A positive Western blot was found in 55.5% of serum samples from patients with primary biliary cirrhosis 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 an autoimmune response to antigenically related cellular proteins or to a specific antibody response to HIAP proteins expressed as an incidental consequence of attendant pathological processes, the high prevalence of antibodies against HIAP proteins demonstrated in patients with systemic sclerosis may be considered a hallmark of this disease.