N-acetyl-cysteine and L-2-oxathiazolidine-4-carboxylic acid enhance contact-dependent growth of HIV in resting peripheral blood mononuclear cells (PBMC) in vitro and increase recovery of HIV from human-PBMC SCID mice

Abstract

Objectives: To ascertain the effects of N-acetyl-cysteine (NAC) and L-2-oxothiazolidine-4-carboxylic acid (OTC) on HIV replication in resting T lymphocytes mixed with chronically infected U1 promonocytic cells; examine the phenotypes of NAC- and OTC-treated cells; and monitor HIV recovery from hu-PBMC SCID mice (SCID mice infected with HIV-1_BaL reconstituted with human peripheral blood mononuclear cells) treated with oral OTC. Design and Methods: Unstimulated PBMC from uninfected donors preincubated for 2 days with pH-adjusted NAC or OTC were cultured at a concentration of 1 × 10⁶cells/ml with 100 U1 cells that were chronically infected with HIV-1_IIIB. HIV-1 production in the presence or absence of zidovudine was measured by p24 assay at 1–3 weeks, and results were compared with values from the same cell cultures maintained without NAC or OTC exposure. In some experiments U1 cells were separated from PBMC by a 0.4 µm membrane. NAC-treated and -untreated cells were subjected to FACS analysis of multiple-cell-surface adhesion and activation molecules and the results were compared. Hu-PBMC SCID mice were fed OTC for 3 days prior to infection with HIV-1_BaL and for the next 3 weeks. Mice were then sacrificed and peritoneal lavage cells were cultured for virus analysis. Results: Unstimulated, non-dividing PBMC supported high levels of HIV replication when in direct contact with U1 cells in the presence of NAC or OTC; CD2 and CD54 (I-CAM1) were down-regulated on NAC-treated PBMC; and OTC-treated mice produced significantly higher yields of HIV-1 from peritoneal cells than did untreated mice. Conclusions: At concentrations ≤5 mM, NAC and OTC potentiate HIV growth in unstimulated PBMC in vitro and in SCID mice. Caution in the use of these agents as antiviral monotherapies is advisable.