A recombinant human IL-4 mutein numbered in accordance with wild-type IL-4 wherein the mutein comprises at least one amino acid substitution in the binding surface of either the A- or C-alpha helices of the wild-type IL-4 whereby the mutein binds to the IL-4R alpha receptor with at least greater affinity than native IL-4. The substitution is more preferably selected from the group of positions consisting of, in the A-helix, positions 13 and 16, and in the C-helix, positions 81 and 89. A most preferred embodiment is the recombinant human IL-4 mutein wherein the substitution at position 13 is Thr to Asp. Pharmaceutical compositions, amino acid and polynucleotide sequences encoding the muteins, transformed host cells, antibodies to the muteins, and methods of treatment are also described.