The effects of infection with respiratory syncytial virus (RSV) on expression of intercellular adhesion molecule (ICAM)-1 was determined in vitro in nasal epithelial cell cultures. Functional consequences of changes in ICAM-1 expression were assessed by measuring adhesion of a human leukaemic T-cell line to RSV-infected epithelial cells. Also, adhesion of phytohaemagglutinin-activated tonsillar lymphocytes (TL) to RSV-infected epithelial cells caused a significant increase in interleukin (IL)-4 or IL-5 production. Release of these cytokines was adhesion dependent as non-adherent TL produced significantly less IL-4 or IL-5. However, no significant difference was observed for IL-2 or interferon-gamma (IFN-gamma) production. These observations suggest that RSV-infected epithelial cells may induce T-helper type-2 (Th2)-like cytokines by mucosal lymphocytes during mucosal infection in vivo.