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Neutrophils are differentiated, relatively short-lived cells with an extensive array of surface receptors for response to inflammatory and phagocytic stimuli. A prominent feature of these cells is the presence of four distinguishable classes of cytoplasmic granules that contain a remarkable number of factors active in inflammation, tissue repair, and resistance to microbial infection. Blood neutrophils are not end-stage cells but exhibit the capacity for changes in phenotypic characteristics and life span, depending on the stimulating milieu of cytokines and chemokines. Gene expression profiling studies indicate the neutrophil is a transcriptionally active cell, responsive to environmental stimuli, and capable of a complex series of early and late changes in gene expression.

Acronyms and Abbreviations

Acronyms and abbreviations that appear in this chapter include: ADP, adenosine diphosphate; AML1–3, transcription factor for various hematologic lineages; AMP, adenosine monophosphate; ATP, adenosine triphosphate; BPI, bactericidal/permeability-increasing protein; C5a, chemotactic fragment of complement component C5; CAP37, cationic protein of molecular weight 37; CCR, C-C chemokine receptor; C/EBPε, regulating factor of gene expression; CR3, complement receptor 3, also called CD11b/CD18, Mac-1, or integrin αmβ2; CR4, complement receptor 4, also called CD11c/CD18 or integrin αXβ2; CXC, chemokine IL-8; FcαR, receptor I for the Fc region of IgA; FcεRI, receptor I for the Fc region of IgE; FcγRI, receptor I for the Fc region of IgG; FcγRIIA, receptor IIA for the Fc region of IgG; FcγRIIIB, receptor IIIB for the Fc region of IgG; GATA-1, lineage-specific transcription factor; G-CSF, granulocyte colony-stimulating factor; GM-CSF, granulocyte-monocyte colony-stimulating factor; hCAP, human cationic peptide; HNP, human neutrophil peptide; ICAM, intercellular adhesion molecule; Ig, immunoglobulin; IL, interleukin; IL-1RA, interleukin-1 receptor antagonist; JAK2, Janus-associated kinase 2; LFA-1, lymphocyte function antigen-1, also called CD11a/CD18 or integrin αLβ2; LPS, lipopolysaccharide; LTB4, leukotriene B4; MMP-8, metalloproteinase-8, also called collagenase; MMP-9, metalloproteinase-9, also called gelatinase B; NAD, nicotinamide adenine dinucleotide; NADH, reduced form of nicotinamide adenine dinucleotide; NADP, nicotinamide adenine dinucleotide phosphate; NADPH, reduced form of nicotinamide adenine dinucleotide phosphate; NFκB1/p50, transcription factor; PAF, platelet-activating factor; PSGL, P-selectin glycoprotein ligand; PU.1, lineage-specific transcription factor; SNAP, soluble NSF (N-ethylmaleimide-sensitive factor)-attachment protein; TGF, transforming growth factor; TNF, tumor necrosis factor; uPAR, urokinase-plasminogen activator receptor; VAMP, vesicle-associated membrane protein; VEGF, vascular endothelial growth factor.

Circulating neutrophils are not the terminally differentiated short-lived cells without transcriptional activities of earlier conceptualizations. Consideration of the “composition” of the neutrophil should include (1) the prepackaged components of the cell that are released on acute stimulation (i.e., the classic attributes of the neutrophil) and (2) the phenotypic changes in various physiologic and pathologic environments that have functional significance. In addition, considerations of cell composition are most effectively expressed in the context of pathways leading to significant physiologic and pathologic functions.

A prominent characteristic of neutrophils is the abundance of cytoplasmic granules, the features of which are only partially defined. Cell fractionation and ultrastructural studies have ...

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