Neutrophil Function

This chapter provides an overview of the mechanisms of neutrophil adherence, chemotaxis, phagocytosis, and organism killing. Pluripotential hematopoietic stem cells in the bone marrow differentiating in response to specific growth factors give rise to committed progenitors and then neutrophils. These cells are characterized by their multilobed nuclei and abundant granules in the cytoplasm. Mature neutrophils do not multiply, but instead, are continuously replaced. Neutrophils circulate in the blood for only a few hours and survive in the tissue for only a few days; however, this can be extended by a day or two upon their exposure to various activating agents at sites of inflammation. Neutrophils eventually succumb to programmed cell death by an intrinsic or extrinsic apoptotic pathway. Once neutrophils are recruited into the underlying tissue from the blood and encounter a microorganism, they phagocytize and kill the pathogen to eliminate the infection. This chapter discusses congenital and acquired defects in neutrophil function that predispose animals to infection. The chapter also elaborates in detail neutrophil-mediated tissue injury.