Mutant interleukin-2 polypeptides

An isolated mutant interleukin-2 (IL-2) polypeptide, wherein said mutant IL-2 polypeptide comprises the amino acid sequence of SEQ ID NO:

• 1 with up to five amino acid substitutions, wherein said up to five amino acid substitutions comprise three amino acid substitutions that abolish or reduce affinity of the mutant IL-2 polypeptide to a high-affinity IL-2 receptor and preserve affinity of the mutant IL-2 polypeptide to an intermediate-affinity IL-2 receptor, as compared to a wild-type IL-2 polypeptide, wherein said three amino acid substitutions comprise:
• (a) a first amino acid substitution at position 72 of SEQ ID NO:1, selected from the group of L72G, L72A, L72S, L72T, L72Q, L72E, L72N, L72D, L72R, and L72K;
• (b) a second amino acid substitution at position 42 of SEQ ID NO:
• 1, selected from the group of F42A, F42G, F42S, F42T, F42Q, F42E, F42N, F42D, F42R, and F42K;
• and
• (c) a third amino acid substitution at position 45 of SEQ ID NO:
• 1, selected from the group of Y45A, Y45G, Y45S, Y45T, Y45Q, Y45E, Y45N, Y45D, Y45R and Y45K.