The present invention is directed to a method for promoting differentiation, activation and proliferation of human T helper lymphocytes such as those that express IL17 and IL22 (Th-IL17+ and Th-IL22+ T cells) and provides methods for decreasing T cell activation or T cell biological activity, inhibiting an immune response and treating autoimmune diseases by increasing the biological activity of or administering a transcription factor such as a Krüppel-like factor or a forkhead box factor, and pharmaceutical compositions effective for these methods. Also, the present invention provides methods for increasing T cell activation or T cell biological activity, stimulating an immune response and treating diseases such as cancers and infections by decreasing the biological activity of or administering an inhibitor of a transcription factor such as a Krüppel-like factor or a forkhead box factor and pharmaceutical compositions effective for these methods.
