The Ability of Chloroquine To Prevent Tat-Induced Cytokine Secretion by Monocytes Is Implicated in Its In Vivo Anti-Human Immunodeficiency Virus Type 1 Activity

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Abstract
Hydroxychloroquine at 1 μM reduces the load of human immunodeficiency virus type 1 (HIV-1) in patients, whereas chloroquine (CQ) concentrations above 3 μM are required for inhibition of HIV-1 replication in peripheral blood mononuclear cells. Exogenous HIV-1 Tat reaches the cytosol of T cells by using low endosomal pH, and endosome neutralization by CQ prevents Tat from entering and affecting T cells. We show here that 0.6 μM CQ inhibits cytokine secretion induced by Tat in monocytes without affecting lipopolysaccharide-triggered cytokine release. This finding suggests that the in vivo anti-HIV-1 effect of CQ results not from a direct effect on the infected cell but rather from the capacity of CQ to prevent Tat from perturbing the cytokine balance.