Nonspecific Deposition Of IL-8 By Human Neutrophils During Chemotaxis In Vitro

Abstract

Polymorphonuclear neutrophils (PMNs) of the innate immune system are responsible for ingestion and killing of invading microorganisms. However, microbial clearance by PMNs requires chemotaxis along a chemoattractant gradient from the vasculature to an infectious focus. Shown here, treatment of PMNs with fibrinogen enhances migration to the chemoattractant, formyl-methionyl-leucyl-phenylalanine (fMLF), increasing the number of migrating PMNs and migratory distance. Previous studies demonstrated that fibrinogen enhanced MU-stimulated production of another chemoattractant, interleukin-8 (IL-8). IL-8, released by migrating PMNs, could provide an additional chemoattractant for the further migration of additional PMNs, amplifying the inflammatory response. The cationic nature of IL-8 could facilitate its immobilization to the extracellular matrix into chemoattractant "trails." Using "underagarose" chemotaxis and amplified immunofluorescence staining, areas of extracellular IL-8 staining were identified; however, instead of specific deposition of IL-8, these areas appeared to result from nonspecific deposition of cellular debris since they contained other cellular components such as B-actin.