Table 3.

Summary of Kinetic Measurements

Binding of sCD80 to		Immobilization level*		k on (× 10−5 M−1s−1)		k off (s−1)		K dcalc (k off/k on, μM)
CTLA-4 Ig		High		6.2 ± 1.8§ (n = 3)		0.24 ± 0.03 (n = 3)		0.3
		High (linear regression)‡		3.4 (n = 1)		0.2 (n = 1)		0.63
		Low		9.4 ± 0.3 (n = 2)		0.43 ± 0.03 (n = 3)		0.46
CD28 Ig		High		4.7 ± 0.6 (n = 4)		1.1 ± 0.15 (n = 3)		2.3
		Low		6.6 ± 0.8 (n = 4)		1.6 ± 0.1 (n = 4)		2.4

^* CTLA-4 Ig or CD28 Ig were immobilized directly. For CTLA-4 Ig, high and low levels were 2,500 and 900 RUs, respectively. For CD28 Ig, high and low levels were 6,200 and 3,400 RUs, respectively.  

^‡ Data from Fig. 4 E.  

^§ The values shown are the mean of n determinations (± SD for n ⩾3 or ± range for n = 2).