The present invention relates to a novel epitope to convert T cell to type 2 helper T (TH2) cell. Specifically, the present invention relates to an epitope constituting the 20th to 30th amino acids (SEQ ID No. 2) of extracellular domain (ECD) of activation-inducible tumor necrosis factor receptor (AITR), an antibody recognizing the epitope, a polynucleotide encoding the epitope, a polynucleotide encoding the antibody, an expression vector comprising the polynucleotide encoding the epitope or antibody, a transformant introduced with the vector, a composition comprising the antibody for converting T cell to TH2 cell and a method of conversion, a pharmaceutical composition comprising the antibody for preventing or treating autoimmune disease, and a method for treating autoimmune disease using the antibody.
