The initial biologic function of TSLP demonstrated that it interacted with DC to promote Th2 cell differentiation and thus promoted allergic disease.41,53 TSLP stimulation of CD11b+ DC upregulates OX-40L that interacts with OX-40 on CD4 T cells to promote a Th2 response.42,43 The survival and maintenance of ILC2 that produce Th2-type cytokines, depends on the presence of TSLP.54,55 In addition, TSLP signaling instructs DCs to produce CCL-22,28 a chemokine that recruits Th2 cells through its interaction with the CCR4 receptor. The gene discussed is TNFSF4; the disease is allergic disease.