Cross -Reactivity of the V3-Specific Antibodies with the Human C1q
Abstract It has been previously shown that the sequence similarity between a portion of the envelope glycoprotein 120 (gp120) from the human immunodeficiency virus type-1 (HIV-1) and several types of human collagen and collagen-like molecules exists. That observation led to the suggestion that the antibodies against the third hypervariable region (V3) of HIV-1 gpl20 (V3-specific antibodies) might have a role in the autoimmune phenomena observed in HIV-infected persons. In this study we have examined the cross-reactivity of the V3-specific anti bodies purified from sera of HIV-infected individuals, sera obtained from the rheumatoid arthritis and systemic lupus erythematosus patients, as well as from the sera of healthy volun teers with the separate chains of a subcomponent of the first component of the human com plement system, C1q. Our results show that the V3-specific antibodies are present in the sera of the HIV-infected individuals, patients suffering of the systemic autoimmune diseases as well as in the sera of healthy volunteers. Whereas these antibodies appeared in the HIV+-sera after antigen challenge, those present in the H IV --sera probably represent the antibod ies that are cross-reactive with the antigen. V3-reactive antibodies can be purified by affinity chromatography and they were highly specific for the V3-peptide. Additionally, they showed cross-reactivity with the separate chains of the human C1q as well as with the chicken colla gen type VI. Possible physiological implications are discussed.