Greater clinical benefit in controlling the symptoms of asthma is frequently observed through combining moderate doses of inhaled glucocorticoids together with longacting 2-agonists, as compared to increasing glucocorticoid dosage alone. In order to address in vitro whether glucocorticoids plus 2-agonists, in comparison to glucocorticoids alone, have greater inhibitory activity on CD4+ T cell responses to allergen, peripheral blood CD4+ T cell responses to allergen were compared in the presence or absence of the glucocorticoid fluticasone proprionate and the short and long acting 2-agonists salbutamol and salmeterol respectively. Fluticasone proprionate inhibited interleukin (IL-)5 and IL-13 and enhanced IL-10 synthesis in allergen stimulated cultures in a concentration dependent manner. Salmeterol, but not salbutamol, inhibited IL-5 and IL-13 and enhanced IL-10 synthesis in these cultures. When used in combination the two drugs demonstrated an additive effect on this pattern of cytokine production. Allergen-specific T cell lines induced in the presence of salmeterol and fluticasone proprionate inhibited IL-5 and IL-13 production by allergen-specific Th2 cell lines in an IL-10 dependent manner. Thus fluticasone proprionate and salmeterol increased IL-10 and reduced Th2 cytokine synthesis additively in allergen stimulated human CD4+ T cells.