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

Lucia Lopalco*, Claudia Pastori, Antonio Cosma, Samuele E. Burastero, Brunella Capiluppi, Enzo Boeri, Alberto Beretta, Adriano Lazzarin, Antonio G. Siccardi

*Corresponding author for this work

Research output: Contribution to journalArticleResearchpeer-review

45 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)109-115
Number of pages7
JournalAIDS Research and Human Retroviruses
Issue number2
Publication statusPublished - 2000
Externally publishedYes


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