Effectiveness of omalizumab in a patient with severe asthma, low serum IgE level, and lack of sensitized allergens induced by oral steroid therapy: the usefulness of impulse oscillation for assessment of omalizumab therapy.

BACKGROUND: Omalizumab is a humanized monoclonal anti-IgE antibody that was recently approved for the treatment of severe allergic asthma. However, omalizumab is not licensed for allergic asthma in patients with a low serum IgE level (<30 IU/mL) or negative results for specific allergen tests.

CASE HISTORY: We present a patient with severe asthma and low serum IgE levels who had negative results for specific allergens induced by oral steroid therapy. Omalizumab administration improved asthma exacerbated forced expiratory volume in 1 s (FEV(1)) and respiratory resistance measurements based on the impulse oscillation technique (Mostgraph-01). The response to omalizumab therapy was evidenced by a decrease in airway resistance at 1 month.

CONCLUSIONS: The findings of this case report indicate that omalizumab treatment had beneficial effects in a patient with severe asthma and low total serum IgE levels with negative results for specific IgE, which may have been induced by long-term corticosteroid administration.