Anti-cell antibodies in exposed seronegative individuals with HIV type 1-neutralizing activity

• Published in: AIDS research and human retroviruses Vol. 16; no. 2; p. 109
• Main Authors: Lopalco, L, Pastori, C, Cosma, A, Burastero, S E, Capiluppi, B, Boeri, E, Beretta, A, Lazzarin, A, Siccardi, A G
• Format: Journal Article
• Language: English
• Published: United States 20.01.2000
• Subjects: Autoantibodies - blood; CD4 Antigens - immunology; Female; Genotype; HIV Antibodies - blood; HIV Infections - epidemiology; HIV Infections - genetics; HIV Infections - immunology; HIV-1 - immunology; HIV-1 - isolation & purification; HLA Antigens - immunology; Humans; Immunoglobulin G - immunology; Italy - epidemiology; Male; Polymerase Chain Reaction; Precipitin Tests; Receptors, CCR5 - genetics; Seroepidemiologic Studies
• ISSN: 0889-2229
• DOI: 10.1089/088922200309458

Despite repeated exposures to HIV-1, some individuals remain seronegative. This study reports that sera from a fraction of exposed seronegative (ESN) subjects showed HIV-neutralizing activity; 5 of 17 ESN sera and none of 17 controls neutralized two different HIV-1 primary isolates (range of neutralizing titers: 1/20 to 1/60). The neutralizing activity was associated with the IgG fraction of 4 of 4 neutralizing ESN sera. Moreover, in 11 of 17 and 9 of 17 ESN sera (but none of the control sera) we found antibodies against HLA class I and CD4, respectively. One of the ESN sera (EU22) neutralized efficiently the primary virus derived from the seropositive partner and showed a good broadly cross-reactive neutralization. Immunoadsorption of two IgG fractions from EU19 and EU22 on peripheral blood mononuclear cells (PBMC) removed virus-neutralizing antibodies. The correlations between the ESN status and neutralizing activity (p<0.05), anti-HLA antibodies (p<0.0002), and anti-CD4 antibodies (p<0.001) were statistically significant. However, there was no statistically significant correlation between neutralizing activity and either anti-HLA or anti-CD4 antibodies. It can therefore be said that exposure to HIV-1 without seroconversion is, in some individuals, associated with HIV-neutralizing antibodies (not directed against viral antigens) and/or with anti-cell autoantibodies, which are possibly specific for cellular antigens involved in the infection/entry process.