This invention provides nucleic acid molecules encoding mutant human interleukin
13 molecules showing varying specificity for the restricted (IL4 independent) IL13
receptor. The mutant hIL13 molecules include those made by substituting the amino
acid residues that occur in the alpha-helix regions of native hIL13 with various
other amino acid residues. Some of the mutants retain the ability to bind and cause
signaling through IL13 receptors, while other mutants do not.
