It is well known that eosinophils are involved in tyrosine nitration. In this study, we evaluated tyrosine
nitration by rat eosinophils isolated from peritoneal fl uid and constituent eosinophils in the
stomach. Rat peritoneal eosinophils activated with 1 μM phorbol myristate acetate (PMA) and 50
μM NO2
ン showed immunostaining for nitrotyrosine only in smaller cells, despite the fact that eosinophils
are capable of producing superoxide (O2·ン). Free tyrosine nitrating capacity after incubation
with PMA and NO2
ン was 4-fold higher in eosinophils than in neutrophils. Catalase and ク- and コ
-tocopherol inhibited free tyrosine nitration by reactive nitrogen species from eosinophils but not
that by peroxynitrite. Superoxide dismutase augmented free tyrosine nitration by activated eosinophils
and peroxynitrite. The concentration of nitric oxide released from eosinophils was relatively
low (0.32 μM/106 cells/h) and did not contribute to the formation of nitrotyrosine. On the other hand,
most constituent eosinophils constituent in the rat stomach stimulated by PMA and NO2
ン showed
tyrosine nitration capacity. These results suggest that intact cells other than apoptotic-like eosinophils
eluted in the intraperitoneal cavity could not generate reactive species responsible for nitration
by a peroxidase-dependent mechanism. In contrast, normal eosinophils in the stomach were capable
of nitration, suggesting that the characteristics of eosinophils in gastric mucosa are diff erent from
those eluted in the peritoneal cavity.</p