Table 2.
Equilibrium binding of IL-4 variants to IL4-BP and to the receptor on T cells is similar but differs from their T cell proliferative activity
IL-4 variant |
Kd (IL4-BP), nM
|
Equilib. Kd (T cells), nM | EC50 for T cell proliferation, nM | |
---|---|---|---|---|
koff/kon | Equilib. | |||
IL4 | 0.16 | 0.11 | 0.12 | |
I5A | 1.2 | 1.1 | 0.83 | 0.08 |
T6A | 0.14 | 0.06 | 0.11 | |
Q8A | 0.16 | 0.1 | ||
E9Q | 31 | 24 | 16* | 3.1 |
E9A | ND | |||
I11A | 0.18 | |||
K12S | 0.15 | |||
T13A | 0.84 | 0.83 | 0.5 | 0.12 |
N15A | 0.15 | 0.11 | ||
S16A | 0.12 | 0.11 | ||
E19A | 0.094 | 0.13 | ||
R53Q | 0.66 | 0.72 | 0.68* | 0.13 |
K77A | 0.21 | |||
Q78A | 0.2 | |||
R81A | 0.36 | 0.08 | ||
F82A | 0.14 | 0.1 | ||
K84A | 0.29 | 0.1 | ||
R85A | 0.33 | 0.09 | ||
R88Q | 19 | 19 | 20* | 2.5 |
R88A | 92 | 110 | 140 | 8.1 |
N89A | 2.3 | 1.5 | 2.3 | 0.09 |
W91A | 0.55 | 0.56 | 0.25 | 0.09 |
The Kd values of IL-4 variants were calculated from the kinetic constants of Table 1 (Kd = koff/kon) and from equilibrium binding to biosensor-immobilized IL4-BP. The Kd values for IL-4 variants and the receptor on T cells were determined by competitive radioligand binding. The EC50 values are the concentrations effecting half-maximal proliferation of T cells. ND, not determined.
*Data from ref. 11.