Close encounters of neutrophils and DCs.

Neutrophils have a major function in innate immunity that involves phagocytosis and the killing of bacteria. Neutrophils also release pro-inflammatory chemokines and cytokines in response to pathogens that attract and stimulate other immune cells. This provides neutrophils with the potential to orchestrate adaptive immune responses. Here, we propose that neutrophils regulate adaptive immunity through interactions with dendritic cells (DCs). Neutrophils might function as danger sensors that communicate the presence of infection to DCs and instruct them to tailor ensuing immune responses to the type of pathogen. We also discuss how neutrophils trigger DC maturation and instruct DCs to induce Th1-type T-cell responses, and define the underlying molecular mechanisms that involve binding of Mac-1 on neutrophils to DC-SIGN on DCs.