['A T(H)1-specific transcription factor, T-box-containing protein expressed in T cells (T-bet), controls the production of both T(H)1 and T(H)2 cytokines in T(H) cell differentiation by means of distinct mechanisms. T-bet-deficient mice overproduce T(H)2 cytokines and have spontaneous airway inflammation.', 'We tested whether T-bet overexpression could protect against the development or progression of asthma.', 'We generated a T cell-specific and inducible line of T-bet-transgenic mice on a T-bet-deficient genetic background and used it to study the function of T-bet in an ovalbumin (OVA)-induced asthma model.', 'Induction of T-bet in a T cell-specific manner in an OVA model of asthma concomitant with OVA injection prevented airway hyperresponsiveness, eosinophilic and lymphocytic inflammation, and IL-5 and IL-13 production in bronchoalveolar lavage fluid and also reduced serum IgE and T(H)2 cytokine production by peripheral T cells. Even when T-bet expression was induced during later stages of asthma progression, T-bet overexpression still attenuated airway hyperresponsiveness and goblet cell hyperplasia, as well as T(H)2 cytokine production.'] Does restoration of T-box-containing protein expressed in T cells protect against allergen-induced asthma?