Many patients with asthma have persistent symptoms associated with chronic inflammation despite treatment with corticosteroids. Novel approaches to the treatment of such patients include the administration of therapies targeting specific cytokines believed to be involved in persistent airway inflammation.1,2 One such candidate is thymic stromal lymphopoietin (TSLP). This cytokine upregulates the expression of OX40 ligand (OX40L) on dendritic cells, which interacts with OX40 on T cells to promote the production of TH2 cytokines such as IL-4, IL-5, and IL-13.3 TSLP has other proinflammatory effects, including the upregulation of cytokine and chemokine production from dendritic cells and mast c