The present invention relates to novel full-length interferon gamma (IFNG) polypeptide variants having interferon gamma activity. The full-length interferon gamma polypeptide variants of the invention are obtained by performing selected modifications in the C-terminal part of the molecule. The full-length interferon gamma polypeptide variants of the invention are useful in therapy, in particular for the treatment of interstitial pulmonary diseases, such as idiopathic pulmonary fibrosis.