Table 1.

Comparative binding affinities and kinetics of XOMA 052 binding to IL-1β from different species determined by Biacore

Species	ka (M−1s−1)	kd (s−1)	KD (pM)
Human	1.7 × 106	≤6.3 × 10−6	≤4 ± 2*
Rhesus	8.5 × 105	≤6.6 × 10−6	≤8 ± 2*
Rat	1.5 × 106	≤2.8 × 10−6	≤2 ± 1*
Mouse	7.7 × 105	2.4 × 10−3	3000 ± 100

^*The kinetics of the interaction between XOMA 052 and IL-1β from these three species are at the limit of measurement by Biacore, and therefore the K_D values in this table represent upper limits of K_D (i.e., lower limits of affinity). Error values reflect the range derived from replicate kinetic titration experiments.