Technique for quantification of LTB4-lnduced changes in peripheral granulocyte counts in vivo in the rabbit

Abstract A method to quantify leukotriene B 4 -(LTB 4 )-induced changes in peripheral granulocyte counts in the rabbit is described. Rabbits were surgically prepared with vascular access ports cannulating the right external jugular vein. This preparation made possible rapid, accurate, and repeated sampling of venous blood. Intravenous infusion of LTB 4 (0.5–2 μg mL ) into the left marginal ear vein was found reproducibly to cause an initial, rapid (1–5 min) leukopenia (64%–100% reduction) followed by an extended (20–30 min) leukocytosis (121%–178% increase). Saline infusion for 30 min resulted in no changes in peripheral granulocyte number. The method described was sensitive and reproducible enough to allow evaluation of the LTB 4 receptor antagonist, LY223982 (10 mg kg , i.v.), which was shown to block both the leukopenia and the leukocytosis induced by LTB 4 infusion.