The selectivity of PGD₂ as an eosinophil chemoattractant.

The chemotactic effects of PGD₂ and other eicosanoids on human eosinophils (A) and human neutrophils (B) were examined by means of a modified Boyden chamber assay followed by staining with hematoxylin and chromotrope 2R and counting cells that had migrated through to the bottom of the filter under a microscope. The results are expressed as percentages (± SE) of the maximal responses to 5-oxo-ETE (493 ± 68 cells per 5 high-power fields). Although it is not apparent from the Figure, a concentration of 1 μM 5-oxo-ETE induces close to the maximal response, with relatively little additional effect observed at higher concentrations. The number of cells migrating through the filter in control experiments with vehicle alone was 26 ± 4 cells per 5 high-power fields. Experiments were performed in duplicate on cells from the numbers of different individuals indicated for PGD₂ (●; n = 8), 5-oxo-ETE (○, 5o-ETE; n = 8), PGF_2α (▴; n = 4), PGE₂ (▿; n = 3), and the TXA₂ agonist U46619 (■; n = 3).