CONJUNCTIVAL LEUKOCYTE INFILTRATION EVOKED BY LEUKOTRIENES - DIFFERING RESPONSES AMONG RODENT SPECIES

Application of leukotrienes (LT) B-4 or D-4 to the guinea-pig eye evok es conjunctival eosinophil infiltration, providing an in vivo model of tissue eosinophilia. To determine if other rodent species would respo nd similarly, LTB(4) or LTD(4) were applied to the right eye of male m ice and rats (three per group) at doses of 250, 1000 or 5000 ng/eye (m ice) and 1000 or 5000 ng/eye (rats). Left eyes received the same volum e (mice, 5 mu l; rats, 20 mu l) of vehicle (isotonic saline). Conjunct ivae were evaluated histologically 6 h after application. In mice, 100 0 or 5000 ng/eye LTB(4) resulted in mild conjunctival neutrophilia, bu t no leukocyte response to LTD(4) was observed. In rats, no leukocyte responses, either to LTB(4) or to LTD(4), were observed. The results i llustrate interspecies differences in leukocyte responsiveness to LT a nd indicate specifically that, unlike the guinea pig, neither mouse no r rat responds to LT with conjunctival eosinophilia.