Table 3. Competition binding studies: K_i for HABs and LABs with PK11195 and PBR28.

Donor number	Ki (nmol/L) of PK11195	Ki (nmol/L) of PBR28 using single-site fit	Ki (nmol/L) of PBR28 for both binding sites in which data fitted fit model
			High-affinity site	Low-affinity site	Fraction of high-affinity sites
HABs
1	39.4	4.4
2	15.3	3.3
3	22.2	3.0
4	40.0	3.6
7	23.8	3.0
8	15.7	27.3a	4.1	310	0.55
9	38.6	43.7a	7.1	313	0.52
10	28.9	3.1
11	24.6	55.3a	1.3	221	0.41
12	15.3	22.4a	3.3	409	0.58
Mean±s.d.	26.4±10.0 (n=10)	3.4±0.5 (n=6)	4.0±2.4 (n=4)	313±76.8 (n=4)	0.52±0.07 (n=4)
LABs
5	21.8	178.4
6	28.3	194.9
20	24.7	194.1
21	21.7	206.4
22	15.0	166.7
Mean±s.d.	22.3±4.9 (n=5)	188±15.6 (n=5)
T-test (HABs versus LABs)	P=0.41	P<0.0001

HABs, high-affinity binders; LABs, low-affinity binders.

^aData did not fit a single-site model and was therefore excluded from calculation of mean K_i.