Abstract: AimTo investigate the effect of ginkgolide B on PAF-induced adhesion, chemotaxis and degranulation of rat polymorphonuclear leukocytes (PMNs). MethodsThe adhesion of rat PMNs to rat synovial cells (RSC) was measured with MTT colorimetry. The chemotaxis of PMNs was quantified with Boyden chamber method. The degranulation of rat PMNs was evaluated by determining the activity of released β-glucuronidase. ResultsIn comparison with control, ginkgolide B at the concentration of 10 μmol·L^-1 significantly inhibited the adhesion of PMNs to RSC by 71.74%. At the final concentration of 1-1 000 nmol·L^-1, ginkgolide B dose-dependently inhibited the chemotaxis of PMNs stimulated with 10 nmol·L^-1 platelet-activating factor (PAF), the IC₅₀ was 4.84 nmol·L^-1. At the final concentration of 0.01-10 μmol·L^-1, ginkgolide B decreased the release of β-glucuronidase in PMNs induced by 1 μmol·L^-1 PAF in dose-dependent manner. The IC₅₀ was 3.56 μmol·L^-1. ConclusionGinkgolide B was found to significantly inhibit PAF-induced adhesion, chemotaxis and degranulation in rat polymorphonuclear leukocytes. These effects might be considered a part of the mechanisms underlying the antiinflammatory action of ginkgolide B.