Release of anti-HIV mediators after administration of leukotriene B4 to humans.

Background: CD8(+) T cells can control human immunodeficiency virus (HIV) through the lysis of infected cells and the release of soluble mediators, such as macrophage inflammatory protein (MIP)-1 beta, which prevent entry of HIV and/or inhibit HIV replication. Because neutrophils represent a major source of alpha-defensins and, to a lesser extent, MIP-1 beta, we determined whether leukotriene B(4) (LTB(4)), a potent neutrophil agonist, would trigger the release of these 2 anti-HIV peptides.

Methods: Plasma samples from HIV-uninfected subjects receiving intravenous bolus of LTB(4) were analyzed for alpha-defensins and MIP-1 beta levels by use of enzyme-linked immunosorbent assay. Furthermore, in vitro analysis of intracellular and secreted levels of alpha-defensins of resting and LTB(4)-activated neutrophils from HIV-uninfected and HIV-infected subjects were determined. LTB(4) modulation of CD63 and CD66b markers associated with degranulation were studied by use of flow cytometry. Chemotaxis of neutrophils from HIV-uninfected and HIV-infected subjects toward LTB(4) or interleukin (IL)-8 was determined by use of migration assays.

Results: Administration of LTB(4) to humans caused a dose-dependent plasmatic increase in alpha-defensins and MIP-1 beta proteins, with peak levels observed 2 h after administration of LTB(4). Neutrophils isolated from HIV-infected and HIV-uninfected subjects contained similar levels of stored alpha-defensins that were effectively secreted in vitro, in response to LTB(4) activation. Chemotaxis of neutrophils toward LTB(4) or IL-8 was identical among the groups of subjects.

Conclusion: LTB(4) induced the secretion alpha-defensins and MIP-1 beta. Neutrophils from HIV-infected subjects were fully responsive to LTB(4), which highlights a potential usefulness of this lipid mediator in the management of HIV infection.