Interleukin-8 priming of human neutrophils is not associated with persistently altered calcium fluxes but is additive with lipopolysaccharide.
Interleukin-8 (IL-8) priming was studied in neutrophils to examine its dependency on altered calcium fluxes and for similarity to lipopolysaccharide (LPS). IL-8 caused a rapid rise in [Ca2+]i that returned to baseline values by 20 min. Peak [Ca2+]i transients in response to N-formyl-methionyl-leucyl-phenylalanine (fMLP) were unaltered in IL-8-primed compared with unprimed cells. In comparison to LPS and tumor necrosis factor (TNF), IL-8 was a much weaker priming agent as measured by either O2- or H2O2 production. Despite their large disparity in potency, IL-8 and LPS printing were additive using fMLP, a receptor-dependent stimulator, and synergistic using the post-receptor, protein kinase C activator, phorbol 12-myristate 13-acetate (PMA) to trigger the respiratory burst. In contrast, IL-8 and TNF priming were synergistic for fMLP (P = 0.05), but completely nonadditive when PMA was used as the neutrophil stimulant (P = 0.05 for subadditivity). Thus, lasting alterations in [Ca2+]i are not a necessary characteristic of IL-8-primed cells. IL-8 and LPS appear to prime by non-overlapping pathways, whereas IL-8 and TNF appear to share mechanisms distal to protein kinase C activation. IL-8 and LPS may independently contribute to neutrophil-mediated host defense or injury by priming through distinct pathways.
Critical Care Medicine Department, Warren Grant Magnuson Clinical Center, National Institutes of Health, Bethesda, Maryland 20892-1662, USA.
A L
AL
Van Dervort
C
C
Lam
S
S
Culpepper
A F
AF
Tuschil
R A
RA
Wesley
R L
RL
Danner
D000704:Analysis of Variance; D002118:Calcium / Q000097:blood*; D015936:Complement C5a / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004357:Drug Synergism; D006801:Humans; D006861:Hydrogen Peroxide / Q000097:blood; D066298:In Vitro Techniques; D016209:Interleukin-8 / Q000494:pharmacology*; D007700:Kinetics; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008163:Luminescent Measurements; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000187:drug effects / Q000502:physiology*; D016897:Respiratory Burst / Q000187:drug effects / Q000502:physiology*; D013481:Superoxides / Q000097:blood; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D016209:Interleukin-8; D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha; D013481:Superoxides; D009240:N-Formylmethionine Leucyl-Phenylalanine; D015936:Complement C5a; D006861:Hydrogen Peroxide; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium