EFFECT OF TYB-2285 ON ANTIGEN-INDUCED ACCUMULATION OF EOSINOPHILS INTO THE PERITONEAL-CAVITY OF RATS SENSITIZED WITH ASCARIS-SUUM EXTRACT

1. The present study was carried out to investigate the effect of 3,5- bis-(acetoxyacetylamino)-4-chloro-benzonitrile (TYB-2285) on the accum ulation of eosinophils in the peritoneal cavity of Wistar rats sensiti zed with Ascaris suum extract (Asc). 2. Rats were sensitized by IP inj ection of Asc on day 0 and were challenged by IP injection of Asc on d ay 7. Antigen challenge caused a specific, delayed infiltration of eos inophils into the peritoneal cavity that was inhibited by PO administr ation of TYB-2285, but not by ketotifen fumarate, in a dose-dependent manner (3-30 mg/kg). 3. TYB-2285 inhibited the infiltration of eosinop hils when during the induction phase, but not during the effector phas e. The inhibitory effect of TYB-2285 when during the induction phase w as stronger than any other antiallergic drugs, such as tranilast, azel astine, ibudilast, repirinast, tazanolast, oxatomide, or pemirolast. 4 . Transfer of lymphocytes, but not serum, from sensitized rats to inta ct rats provoked a remarkable infiltration of eosinophils after the an tigen challenge. In the experiment of adoptive transfer in rats, TYB-2 285 was effective when given to donor rats. 5. These results demonstra te that TYB-2285 inhibits the accumulation of eosinophils presumably b y inhibiting antigen recognition. Copyright (C) 1997 Elsevier Science Inc.