Effect of quinupristin/dalfopristin on production of cytokines by human monocytes

The effect of the novel streptogramin antibiotic quinupristin/dalfopristin (synercid) on cytokine production in vitro was examined in monocytes obtained from healthy human volunteers and stimulated with either lipopolysaccharide or heat-killed Staphylococcus aureus (Pansorbin), Synercid at concentrations that are achievable in humans (1, 5, and 10 mu g/mL) significantly suppressed production of interleukin (IL)-1 alpha, IL-1 beta, IL-6, IL-10, granulocyte-macrophage colony-stimulating factor, and tumor necrosis factor-or in a concentration-dependent manner. Thus, synercid possesses significant immunomodulatory activity, in addition to its antimicrobial activity.