IL-6 induced an increase in productive infection of MDM with primary viral isolates.

Six-day MDMs cultured in the absence or in the presence of IL-6 were infected with X4 HIV-1 primary viral isolates: 2166 (clade E), 2314 (clade BF), 1954 (clade D), and 1650 (clade A). Infected MDMs were cultured in the presence of cytokines. Viral replication was monitored by p24 measurements. Data represent fold increase ± SEM in p24 production (day 17) from the duplicate cultures of IL-6–treated macrophages compared with p24 production in infected macrophages in the absence of cytokine.