HETEROGENEITY IN EXPOSED UNINFECTED INDIVIDUALS

In spite of repeated exposures to HIV, some individuals remain seroneg ative and apparently uninfected. A variety of mechanisms potentially a ble to confer resistance to HIV infection, including cell-mediated and (unconventional) humoral immune responses, as well as mutations affec ting receptors for virus entry have been considered and analysed. In t his article, we want to discuss recent reports on specific immune resp onses and genetic factors potentially involved in mechanisms of protec tion, and to present some of our data relative to a cohort of people s exually exposed to HIV-1, but persistently seronegative. These EU (exp osed uninfected) individuals can be distinguished from ''normal'' unex posed controls on the basis of significantly increased frequencies of a number of immunological parameters that might be considered ''unconv entional'' correlates of HIV infection/protection. However; EU individ uals are highly heterogeneous since the various unconventional immune responses considered can be present in all possible combinations. Aim of future research will be to ascertain the role of such immune respon ses in the maintenance of the protection state, or their secondary nat ure as signals of a particular kind of infection.