TY - JOUR T1 - Ketotifen inhibits PAF-induced actin polymerization in a human eosinophilic leukaemia cell line, EoL-1 JF - European Respiratory Journal JO - Eur Respir J SP - 1173 LP - 1178 DO - 10.1183/09031936.93.03101173 VL - 3 IS - 10 AU - M Morita AU - S Tsuruta AU - KJ Mori AU - M Mayumi AU - H Mikawa Y1 - 1990/11/01 UR - http://erj.ersjournals.com/content/3/10/1173.abstract N2 - The inhibitory effect of ketotifen on platelet activating factor (PAF)-induced actin polymerization in a human eosinophilic leukaemia cell line, EoL-1, was examined by flow cytometry with the use of reagents specific for the filamentous form of actin (F-actin). Actin polymerization has been considered to be essential for locomotion of cells, chemotaxis and chemokinesis, and thus it reflects the chemotactic reaction of EoL-1 cells stimulated by PAF. Unstimulated EoL-1 cells showed little PAF-induced actin polymerization, whereas EoL-1 cells cultured for 9 days with the supernatant of a human ATL cell line, HIL-3 (HIL-3 sup), showed marked actin polymerization when stimulated with PAF. The actin polymerization in EoL-1 cells induced by PAF was seen in a dose-dependent manner at concentrations of 10(-10) M to 10(-6) M of PAF, and the maximum effect was seen at 10(-7) M of PAF. CV-3988, a specific antagonist of PAF, inhibited 80% of the actin polymerization in EoL-1 cells induced by PAF at a concentration of 10(-5) M. Ketotifen inhibited up to 40% of the PAF-induced actin polymerization of EoL-1 cells in a dose-dependent manner at concentrations of 10(-9) M to 10(-5) M. These results suggest that ketotifen may play an important role in the prevention of eosinophil-induced inflammation in allergic disorders by inhibiting PAF-induced chemotaxis of eosinophils. ER -