Effect of Pseudomonas aeruginosa on interleukin-8 release from human phagocytes.

Pseudomonas aeruginosa infections are commonly observed in sepsis, burns, as well as cystic fibrosis (CF). Among the professional phagocytes neutrophils and monocytes are recruited by various chemotactic factors from the cellular environment. Although they provide the first line of host defense excessive neutrophil accumulation seems to be a major cause of pathogenesis during P. aeruginosa infection. Interleukin-8 (IL-8) represents one important chemoattractant for professional phagocytes. To evaluate IL-8 releasability by phagocytes in the context of P. aeruginosa infection and especially of CF, we stimulated human polymorphonuclear neutrophilic granulocytes (PMN) and peripheral blood mononuclear cells (PBMC) as a source for monocytes with clinical P. aeruginosa isolates, with mucoid P. aeruginosa strain (CF3M) and its nonmucoid revertant (CF3), and with purified P. aeruginosa mucoid exopolysaccharide (alginate). A significant increase in IL-8 release as compared to unstimulated cells was observed after an incubation time of 90 min for PMN and after 60 min for PBMC which increased (PMN: up to 60-fold; PBMC: up to 40-fold) over time (up to 4 h). In contrast of PBMC, when PMN were studied, intracellular IL-8 exceeded the IL-8 release in unstimulated as well as in stimulated cells by up to 10-fold. All clinical P. aeruginosa isolates, independent of the clinical source, induced IL-8 release from human PBMC and PMN in a dose- and time-dependent manner.(ABSTRACT TRUNCATED AT 250 WORDS)