Divergent expression patterns of IL-4 and IL-13 define unique functions in allergic immunity

Interleukin 4 (IL-4) and IL-13 are critical for responses against parasitic helminthes. Here we used genetically engineered reporter mice to assess the temporal and spatial production of these cytokine in vivo. In lymph nodes, IL-4 was confined to T follicular helper (T(FH)) cells, however these cells did not make IL-13. In contrast, tissue type 2 helper T T(H)2 cells produce both cytokines. Divergent IL-4 and IL-13 production also occurred among innate immune cells, where basophils produced IL-4, while innate helper type 2 (Ih2) cells produced IL-13. IL-13 production by T(H)2 and Ih2 cells was dependent on high GATA-3 levels, in contrast to low GATA-3 levels in T(FH) cells and basophils. Distinct localization and cellular expression of IL-4 and IL-13 explains their unique roles during allergic immunity.