Interleukin-13 (IL-13) is one of the cytokines involved in the development of Th2-type immune response. It plays an important role in the pathogenesis of asthma and other allergic diseases. Two deletion forms of IL-13 were constructed on a basis of informational structure analysis and expressed in E. coli cells. They were found to differ in ability to stimulate proliferation of TF-1 cell line. Deletion variant 146 (DV146) completely lacks such activity, whereas DV148 provides about 50% of the proliferation stimulation. The simultaneous addition of DV146 with full-length IL-13 suppresses proliferation depending on the concentration of the deletion form. Thus, the designed protein acts as an antagonist of IL-13.