Fig. 3.
Effect of 15-epi-lipoxin (LX)A4 and compound 43 on interleukin (IL)-8-induced neutrophil chemotaxis. (a) The percentage of inhibition of neutrophil chemotaxis was calculated after preincubation of the compounds (0·1 nM–1 μM) with human peripheral blood isolated neutrophils for 30 min. Briefly, chemotaxis was run for additional 30 min against an IL-8 (1·25 nM) gradient, as described in Material and methods. IL-8-induced neutrophil chemotaxis was dampened by 15-epi-LXA4 (maximum inhibition 40% at 10 nM) and compound 43 (IC50 = 67 nM). SCH527123, a CXCR2 antagonist, was used as a positive control of inhibition of neutrophil migration (IC50 = 9·3 nM). *P < 0·05; ***P < 0·001. (b) Direct chemotactic effect of the reference compounds on neutrophils was measured by incubating 15-epi-LXA4, montelukast, MK-571, SCH527123 (0·1 μM) and compound 43 (0·01, 0·1 and 1 μM) alone in the lower chemotactic chamber compartment without IL-8. Neutrophils were added on top of the filter that separated the upper compartment containing cells, but no agonist, from the lower compartment containing the reference compounds. IL-8 (1·25 nM) was used as a positive control of neutrophil migration and controls of inhibition of IL-8-induced chemotaxis were assessed by incubating compound 43 (0·1 μM) and SCH527123 (0·1 μM) with neutrophils prior to placing them in the upper compartment. ***P < 0·001 IL-8 versus vehicle; *P < 0·05 compound 43 (1 μM) versus vehicle; #P < 0·05 compound 43 and SCH527123 versus IL-8.