A human interleukin 3 analog with increased biological and binding activities

A. F. Lopez, M. F. Shannon, S. Barry, J. A. Phillips, B. Cambareri, M. Dottore, P. Simmons, M. A. Vadas

Research output: Contribution to journalArticlepeer-review

35 Citations (Scopus)


Human interleukin 3 (IL-3) variants generated by site-directed mutagenesis were analyzed in multiple biological and binding assays to identify residues critical for IL-3 activity. Two mutants carrying substitutions in the predicted hydrophilic region within the first α-helix, [Ala21,Leu22]IL-3 and [Ala21Leu22,Ala25IL-3 showed loss of biological activity and high-affinity binding. Mutants in a second predicted hydrophilic region, [Ala44Leu45Ala46]IL-3 and [Ala44,Ala46]IL-3, however, showed similar biological and binding activities to wild-type IL-3. Mutations in a C-terminal hydrophilic region that overlaps the fourth predicted α-helix led to either loss or gain of function. IL-3 analogs [Glu104,Asp105]-, [Leu108]-, [Asn108]-, [Thr108]-, and [Ala101,Leu108]IL-3 were less active than wild-type IL-3, whereas [Ala101,]IL-3 and [Val116,]IL-3 were 2- to 3-fold more potent. Significantly, the double mutant [Ala101,Val116,]IL-3 exhibited a 15-fold greater potency than native IL-3. Receptor binding studies showed that [Ala101,Val116,]IL-3 exhibited increased binding to the high- and low-affinity receptors of monocytes. These results show the generation of an IL-3 analog with increased biological and binding activities and support a model where the C terminus of IL-3 interacts with the a chain of the IL-3 receptor, making this region a useful focus for the development of more potent IL-3 agonists or antagonists.

Original languageEnglish
Pages (from-to)11842-11846
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number24
Publication statusPublished or Issued - 1992


  • Allergy
  • Function
  • Growth factors
  • Hemopoiesis

ASJC Scopus subject areas

  • General

Cite this