SELECTIVE ANTIBODY REACTIVITY WITH PEPTIDES FROM HUMAN ENDOGENOUS RETROVIRUSES AND NONVIRAL POLY(AMINO ACIDS) IN PATIENTS WITH SYSTEMIC LUPUS-ERYTHEMATOSUS

Objective. To investigate antibody responses to a broad panel of pepti des derived from human endogenous retroviruses (HERVs) among unselecte d patients with systemic lupus erythematosus (SLE). Methods. In sera o btained from 69 patients with SLE and healthy blood donors, immunoassa y was used to measure levels of antibody against synthetic peptides de rived from HERVs, exogenous retroviruses, and nonviral poly(amino acid s). Results. Measurement by immunoassay revealed increased frequencies of antiretroviral antibodies against 2 peptides derived from the env gene of the type C-like class, which includes ERV-9 and HERV-H, and ag ainst 2 peptides from the gag region of human T lymphotropic virus typ e I-related endogenous sequence 1, in patients with SLE. Antibodies to 2 nonviral peptides, polyhistidine and polyproline, were also overrep resented in patient sera. In 1 patient, longitudinal data obtained ove r a period of 12 years indicated that the concentrations of certain an tiretroviral antibodies varied according to disease activity. Conclusi on. Reactivity to certain type C HERV-derived antigens was found among patients with SLE. This reactivity could be explained by increased ex posure to cross-reactive epitopes from essentially complete type C HER Vs.