Neurotoxic factors from HIV infected cells: Monocytic cells (THP-1) were infected with HIV-AdaM and culture supernatants were periodically collected, diluted 1:1 in Locke's buffer and analyzed for neurotoxicity on mixed human neuronal cell cultures. (A) Maximal neurotoxicity was noted in supernatants 2 weeks post infection (*P < 0.05). (B) Culture supernatants from days 13 and 15 when immunoabsorbed with antisera to gp120 and Tat show nearly complete blocking of neurotoxicity. Uninfected culture supernatants from corresponding days in both sets of experiments showed <2% neurotoxicity. Each data point represents mean ± SEM from three different cultures.