Human Immunodeficiency Virus Type 1 Infection Modulates the Interleukin (IL)—1β and IL-6 Responses of Human Macrophages to CD40 Ligand Stimulation

Better understanding of the mechanisms of proinflammatory cytokine production during human immunodeficiency virus (HIV) type 1 infection is of pivotal importance. The effect of HIV-1 infection on recombinant CD40 ligand (CD40L)—induced interleukin (IL)—1β and IL-6 production by human macrophages was analyzed. ELISA and cytofluorometric analysis demonstrated that CD40L stimulation of HIV-1—infected macrophages resulted in substantial production of IL-1β and IL-6. In contrast, no cytokine response was observed in uninfected cells. No modulation of the receptor for CD40 was found to account for the enhanced response to CD40L. The CD40L effect was not due to lipopolysaccharide contamination and was completely abrogated by preincubation with a monoclonal anti-CD40L antibody. mRNA studies indicated that the priming effect of HIV-1 on the macrophage response to CD40L was regulated at the transcriptional level. Finally, the effect of HIV-1 on the cytokine response could not be abolished by the HIV-1 protease inhibitor U75875 at concentrations that completely suppressed HIV-1 replication.