Table 4 Human neutrophil states: adhesion, chemotaxis, apoptosis and function

Circulating PMN (resting bloodstream PMN, collected by venipuncture)

Adhesion receptors: constitutive expression of L-selectin, PECAM-1

Chemoattractant receptors: constitutive expression of IL-8 receptor A, IL-8 receptor B, C5aR

Apoptosis receptors: constitutive expression of TNF-α receptor I, Fas, FasL

PMN–EC interactions: baseline PMN rolling, adhesion on activated endothelium and transmigration

Chemotaxis: will undergo chemotaxis to PMN-specific and leukocyte nonspecific chemoattractants

Function: minimal PMN respiratory burst (ROI^•) and microbicidal activity (proteolytic enzymes)

Apoptosis: constitutive apoptosis (PMN half-life ~6 h)

Primed PMN (PMN stimulated with priming agent in vitro)

Adhesion receptors: increased expression of CD11b, L-selectin, PECAM-1, ↔FMLPr

Chemoattractant receptors: ?IL-8 receptor A, ?IL-8 receptor B, ↔C5aR

Apoptosis receptors: ?TNF-α receptor I, ?Fas, ?FasL

Other: CD14, PAFr ↑LTB₄r, ↑PAFr

PMN–EC interactions: unclear impact on rolling, adhesion, diapedesis

Chemotaxis: no change in chemotaxis

Function: when activated, display increased respiratory burst and microbicidal activity after activation

Apoptosis: delayed constitutive apoptosis

Activated PMN (PMN stimulated with activating agent in vitro)

Adhesion receptors: ↑ CD11b, ↑ FMLPr, ?L-selectin, PECAM-1

Chemoattractant receptors: IL-8 receptor A, ↓↓ IL-8 receptor B, ↔C5aR

Apoptosis receptors: unknown

Other: ↓ C3br, ↓ 1C3b

PMN–EC interactions: ↑ PMN rolling and adhesion, ?transmigration

Chemotaxis: ↔chemotaxis to C5a, LTB₄/ZAS; ↑ ?chemotaxis to FMLP

Function: ↑ respiratory burst (ROI^•) and microbicidal activity (proteolytic enzymes); ↑ phagocytosis

Apoptosis: delayed apoptosis

   Exudate PMN (PMN collected from dermal exudate milieu in vivo)

Adhesion receptors: ↑ CD11b, ↑ Mac-1, ↓ L-selectin, ↓ PECAM-1

Chemoattractant receptors: ↓ IL-8 receptor A, ↓ IL-8 receptor B, ↑ C5ar

Function: ↑ FMLPr

Apoptosis receptors: ↓ binding to TNF-α, ?↓ TNF receptor I, ↔Fas, FasL

PMN–EC interactions: unknown

Chemotaxis: ↑ baseline chemotaxis, ↓ chemotaxis to IL-8, ↑ chemotaxis to C5a

Function: ↑ respiratory burst (ROI^•), ↑ microbicidal activity and phagocytosis

Apoptosis: ↓ constitutive apoptosis; ↓ TNF-α-induced, but not Fas-induced apoptosis

   Septic PMN (PMN collected from circulation in septic patients in vivo)

Adhesion receptors: ↓ L-selectin, ?CD11b, ?FMLPr, ?PECAM-1

Chemoattractant receptors: ↓ IL-8 receptor A, ↓ IL-8 receptor B, ↓ C5aR

Apoptosis receptors: ↓ TNF-α receptor I, ?Fas, ?FasL

PMN–EC interactions: unknown

Chemotaxis: ↓ chemotaxis to IL-8 and C5a

Function: ? ↑ respiratory burst (ROI^•), ?↑ microbicidal activity and phagocytosis

Apoptosis: ↓ constitutive apoptosis; ↓ TNF-α-induced, but not Fas induced, apoptosis

Unresponsive or apoptotic PMN

Adhesion receptors: ↓ L-selectin, ?CD11b, ?PECAM-1

Chemoattractant receptors: unknown

Apoptosis receptors: ? ↓ TNF receptor I, ?Fas, ?FasL

Other: ↓ PAFr

PMN–EC interactions: no interaction

Chemotaxis: ↓ chemotaxis

Function: ↓ respiratory burst (ROI^•), ↓ phagocytosis

Apoptosis: unresponsive PMN undergo apoptosis. and apoptotic PMN are unresponsive