Interleukin-2 and use thereof

An IL-2 mutant protein, comprising, as compared to a wild-type IL-2,

• (i) a shortened B′C′ loop region, or
• (ii) a shortened B′C′ loop region and a mutated glycosylation motif,
• wherein the shortened B′C′ loop region has the sequence of A(Q/G)S(K/A) N(F/I)H or SGDASIH positioned between amino acid residues aa72 and aa84;
• wherein the mutated glycosylation motif is a glycosylation motif N-X-S/T introduced by a mutation at amino acid positions selected from the group consisting of:
• 38N-39X-40T/S, 41N-42X-43T/S, 43N-44X-45T/S, 45N-46X-47T/S, 62N-63X-64T/S, 68N-69X-70T/S, 72N-73X-74T/S, and 74N-75X-76T/S, wherein X is any amino acid other than proline, or X is an amino acid same as the amino acid at the corresponding position in the wild-type IL-2 or a conservatively substituted residue thereof;
• wherein the wild-type IL-2 is a human IL-2 comprising the sequence of SEQ ID NO:
• 26;
• and wherein the amino acid positions are numbered according to SEQ ID NO:
• 26.