Interleukin-2 mutants with enhanced alpha-receptor subunit binding affinity.
Stimulation of T-cells by IL-2 has been exploited for treatment of metastatic renal carcinoma and melanoma. However, a narrow therapeutic window delimited by negligible stimulation of T-cells at low picomolar concentrations and undesirable stimulation of NK cells at nanomolar concentrations hampers IL-2-based therapies. We hypothesized that increasing the affinity of IL-2 for IL-2Ralpha may create a class of IL-2 mutants with increased biological potency as compared with wild-type IL-2. Towards this end, we have screened libraries of mutated IL-2 displayed on the surface of yeast and isolated mutants with a 15-30-fold improved affinity for the IL-2Ralpha subunit. These mutants do not exhibit appreciably altered bioactivity at 0.5-5 pM in steady-state bioassays, concentrations well below the IL-2Ralpha equilibrium binding constant for both the mutant and wild-type IL-2. A mutant was serendipitously identified that exhibited somewhat improved potency, perhaps via altered endocytic trafficking mechanisms described previously.
Department of Chemical Engineering and Biological Engineering Division, Massachusetts Institute of Technology, MIT 66-552, Cambridge, MA 02139, USA.
Balaji M
BM
Rao
Andrew T
AT
Girvin
Thomas
T
Ciardelli
Douglas A
DA
Lauffenburger
K Dane
KD
Wittrup
D002455:Cell Division / Q000235:genetics / Q000502:physiology; D003001:Cloning, Molecular; D007376:Interleukin-2 / Q000235:genetics* / Q000378:metabolism*; D053645:Interleukin-2 Receptor alpha Subunit; D009154:Mutation; D011485:Protein Binding / Q000235:genetics / Q000502:physiology; D018123:Receptors, Interleukin / Q000378:metabolism*; D012441:Saccharomyces cerevisiae
D007376:Interleukin-2; D053645:Interleukin-2 Receptor alpha Subunit; D018123:Receptors, Interleukin