The effect of adherence on the generation of reactive oxygen species by human neutrophilic granulocytes

Human neutrophilic granulocytes (PMN) suspended in protein containing salt solution or adherent on protein coated nylon fibers were tested for the production of H₂O₂ and O₂^– in response to various PMN stimulants. Upon stimulation with the chemotactic factors formyl-methionyl-leucyl-phenylalanine, C5a and platelet activating factor, the non-chemotactic ionophore A23187, and the chemotaxis inhibitors tumor necrosis factor (TNF) and lymphotoxin (TNF) adherent PMN produced considerably more reactive oxygen metabolites than suspended cells. The relative amounts of the two metabolites varied with the stimulus and its concentration, TNF and TNF favoring H₂O₂ production, C5a eliciting more O₂^– than H₂O₂ and the other active stimulants being in between. Leukotriene B₄ and a novel monocytederived chemotaxin were inactive in releasing either oxygen derivative from adherent or suspended PMN. The data indicate that attachment of PMN to endothelial cells or to connective tissue substances can strongly enhance its ability to respond to a given stimulus with the production of reactive oxygen metabolites. The findings may in part explain the priming phenomenon since many PMN-priming mediators increase the cells' adherence.