CC chemokines induce neutrophils to chemotaxis, degranulation, and α-defensin release

We have previously shown that a Taiwanese cohort of HIV-uninfected individuals was associated with the significantly elevated levels of serum β-chemokines, macrophage inflammatory protein (MIP-1)-α and MIP-β, and RANTES. In the present study, we report that the members of this cohort have significantly greater numbers of lower buoyant-density neutrophils in their blood, which leads to further investigation of the effects of β-chemokines on neutrophils. By electron and confocal microscopic techniques and FACScan, the results demonstrated that MIP-1α, MIP-β, and/or RANTES readily activated the cells to release a large quantity of α-defensins in vitro through the degranulation process, which was the cause of low-buoyant-density neutrophil production. The purified neutrophils underwent chemotaxis and increased phagocytic capability when β-chemokines were present. Only when using all 3 neutralizing antibodies for CCR1, CCR3, and CCR5 could the chemotaxis of neutrophils be inhibited completely, suggesting that these receptors are involved in transducing activating signals. Because neutrophils are the most abundant white blood cells that can be activated simultaneously to release α-defensins and because these proteins are antiviral, including anti-HIV, our results support the hypothesis that in addition to β-chemokines, the innate immunity of the cohort plays a role in inhibiting the transmission of HIV.