The additive in vitro anti-HIV-1 effect of chloroquine, when combined with zidovudine and hydroxyurea

The 4-aminoquinoline chloroquine and its analogue hydroxychloroquine are endowed with anti-HN-l activity both in vitro and in vivo. We previously reported that the addition of CQ (chloroquine) to the combination of HU (hydroxyurea) and ddI (didanosine) provides additive anti-HIV-l activity. We here extended this in vitro investigation by studying whether the addition of CQ also resulted in additive anti-HIV-1 activity when combined with HU plus AZT (zidovudine). The same effect was found, whether CQ was added to HU plus AZT or to HU plus ddI, in recently infected H-9 and U-937 cells or primary T cells and monocytes, as well as in immunologically or oxidatively stimulated ACH-2 and U-l tells. At concentrations where CQ exerts its anti-HIV-l effect in combination with the other drugs, CQ addition does not result in either cell toxicity or apoptosis. (C) 2001 Elsevier Science Inc. All rights reserved.