Objective: To analyse serological aspects of systemic autoimmunity in HIV-1-seropositive patients and in individuals at risk for AIDS.

Design and methods: The reactivity of antibodies in the serum of 100 HIV-1-seropositive patients was investigated by enzyme-linked immunosorbent assay (ELISA) using a series of antigens known to be recognized by antibodies from patients with multisystemic autoimmune diseases, such as systemic lupus erythematosus, mixed-connective tissue disease and Sjogren's syndrome.

Results: High levels of immunoglobulin G (IgC) antibodies reacting with double-stranded DNA (dsDNA), synthetic peptides of ubiquitinated histone H2A, Sm-D antigen, U1-A RNP antigen and 60 kD SSA/Ro antigen were found in 44-95% of HIV-infected patients. Among histone antibodies, the most frequent reactions were towards the carboxy-terminal region of histone H1 and to histone H2B and its amino-terminal domain 1-25. Eight HIV-1-seropositive patients at different stages of disease according to the Centers for Disease Control classification were also studied. In most cases, no obvious fluctuations were observed over several years. Antibodies were found early, and their specificity and apparent level of activity remained relatively constant. There was no evidence of such an autoimmune response in the serum of high-risk homosexual seronegative men.

Conclusions: Although the aetiology of AIDS is known, in general the aetiology of multisystemic autoimmune diseases remains to be determined, and the sequence of events taking place remains obscure in both cases. It is possible that the large spectrum of antibodies found in HIV-infected patients reflects a specific stimulation of B-cells by nuclear antigens released by apoptosis during an early stage of disease.