A modular interface of IL-4 allows for scalable affinity without affecting specificity for the IL-4 receptor

Table 1 BIAcore analysis of IL-4, IL-13 and variants

IL-4 variant	k _on × 10^-7 [s^-1 M^-1]	k _off × 10³ [s^-1]	app. K _D [nM]	relative K _D (K _D(mut)/K _D(IL-4))
IL4	1.32 ± 0.27	1.26 ± 0.16	0.10 ± 0.02	1.0
T13D	1.27 ± 0.19	0.46 ± 0.16	0.04 ± 0.02	0.4
F82D	1.61 ± 0.15	0.46 ± 0.15	0.03 ± 0.01	0.3
T13D-F82D	1.19 ± 0.18	1.40 ± 0.27	0.12 ± 0.03	1.2
R85A	0.46 ± 0.22	1.58 ± 0.17	0.47 ± 0.34	4.7
T13D-R85A	0.58 ± 0.19	1.38 ± 0.22	0.26 ± 0.08	2.6
F82D-R85A	0.42 ± 0.12	4.10 ± 1.01	1.08 ± 0.50	10.8
T13D-F82D-R85A	0.30 ± 0.08	1.44 ± 0.19	0.51 ± 012	5.1
IL-13 Variant				relative K _D (K _D(mut)/K _D(IL-13))
IL-13	-	-	-	1.0 (150 nM)
E11A	-	-	-	233
R64A	-	-	-	> 1300

Association and dissociation rates of IL-4 variants to immobilized IL4-Rα_ECD were measured on a BIA2000 system. The rate constants represent mean values of 18 independent measurements with 6 different analyte concentrations. Binding affinities of IL-4Rα_ECD to the complex of IL-13/IL-13variant bound to IL-13Rα1 were measured via the COINJECT command. Dissociation constants were obtained from equilibrium binding analysis, therefore no rate constants are given. Binding of the IL-13 variants to IL-13Rα1 was unaltered compared to wild-type IL-13.

ISSN: 1741-7007