Measurement of direct and indirect forms of anti-HIV-1 ADCC: implications for other retroviral disease.

Among the varied cytotoxic immune reactivities elicited as a result of HIV-1 infection are two forms of non-MHC restricted cytotoxicity--namely, indirect and direct ADCC. Since these reactivities are directed at both HIV-1 infected as well as gp120 coated targets, there is a potential for anti-HIV-1 ADCC to play both a beneficial as well as a pathogenic role in the natural history of HIV-1 disease. Resolution of these issues will be of great importance to the development of future preventive and interventive therapeutic strategies for AIDS. The direct and indirect forms of ADCC described herein are, most probably, not unique to HIV-1. In theory, any viral disease, retroviral or otherwise, in which high titers of anti-envelope antibodies persist in an environment rich in Fc-receptor bearing effector NK/K cells would be likely to have some component of direct ADCC as part of the host anti-viral response. With this in mind it is imperative that those researchers involved in characterizing cellular anti-viral cytotoxicities do not mistake direct ADCC for another form of CTL activity. These two highly potent reactivities operate independently and are subject to different control mechanisms, both positive and negative, anti-viral ADCC has too long been regarded as a strictly in vitro phenomenon with no in vivo counterpart. Our studies demonstrating direct forms of ADCC in infected patients will hopefully have some impact in forcing a careful re-evaluation of this extremely important issue.