Fig. 1

Inhibition of nitric oxide synthase prevents superproduction of TNF by LPS-stimulated HIV-1-infected human monocytes

HIV-1-infected and uninfected (control) monocyte cultures prepared from peripheral blood of three seronegative donors were stimulated with 0.5 ng/ml of LPS alone or in combination with l-NMMA (2 mM), d-NMMA (2 mM), or hemoglobin (Hb, 100 µg/ml). At the time of stimulation, RT values in culture supernatants were 0.6 × 10⁶ cpm/ml (A, donor 1), 1.3 × 10⁶ cpm/ml (B, donor 2), and 1.1 × 10⁶ cpm/ml (C, donor 3). Eighteen hours after stimulation, TNF in the culture supernatants was assayed by enzyme-linked immunosorbent assay (ELISA). For a time course experiment (D), HIV-infected and control monocyte cultures prepared from peripheral blood of donor 1 were stimulated with 0.5 ng/ml of LPS alone or in combination with l-NMMA (2 mM), and culture supernatants collected at 8, 24, and 48 hr after infection were assayed by TNF-specific ELISA. Three independent wells for each treatment were analyzed, and the results are presented for each donor as mean ± SD. Statistical analysis of the differences between l-NMMA-treated and untreated HIV-infected cultures was performed using a one-tailed t test; *p < 0.05; **p < 0.01.