['Roxithromycin (RXM), a 14-member macrolide antibiotic, has a variety of bioregulatory functions such as anti-inflammatory effects, anti-oxidant effects, and modulation of immune responses.', 'In this study, we analyzed the effect of RXM on chemokine-induced chemotaxis of Th1, Th2, and regulatory T (Treg) cells established from three normal human peripheral blood lymphocytes by the reported methods.', 'Incubation with 10 microM RXM for 18 h did not alter the expression profile of CXCR3 on Th1 cells and CCR4 on Th2 and Treg cells. However, upon RXM preincubation, the migration of Th1 cells to IP-10 and Th2 cells to TARC was partially suppressed, although RXM did not influence Treg cell migration. Erythromycin and clarithromycin at the same concentration did not exert such effects. F-actin polymerization and Ca(++) influx induced by IP-10 and TARC in Th1 and Th2 cells, respectively, was down-regulated by RXM pretreatment.'] Does roxithromycin inhibit chemokine-induced chemotaxis of Th1 and Th2 cells but regulatory T cells?