Influence of arachidonic acid metabolites in vitro and in uterine washings on migration of equine neutrophils under agarose.

The influence of arachidonic acid metabolites on migration of equine neutrophils under agarose was investigated. Leukotriene B4 (LTB4) was chemotactic at concentrations between 0.1 and 1000 ng ml-1 and prostaglandin E2 (PGE2) at 1 and 10 ng ml-1 but not at higher or lower concentrations. Prostaglandin F2 alpha (PGF2 alpha) was not chemotactic for equine neutrophils at any concentration. Random migration was significantly inhibited (P less than 0.05) by suspension of neutrophils in LTB4 (0.1 to 1000 ng ml-1) and PGF2 alpha (0.1 ng ml-1) but not at high concentrations. There was a significant positive correlation between random migration of neutrophils suspended in uterine washings from persistently endometritic mares and concentrations of endogenous PGF (P less than 0.002) and PGE2 (P less than 0.05) in washings. Thus certain metabolites of arachidonic acid affect migration of equine neutrophils and may play a significant role in recruitment of neutrophils to sites of inflammation in the horse.