Table 2.

Potency of human soluble CR1 LHR-A domain variants in C3b and C4b cofactor activity assays

Human CR1 truncation	Cofactor activity (pM ± SD)
Domain	C4b	C3b
LHR-ABC/CSL040	860 ± 290	78.9 ± 20.2
LHR-A	20,460 ± 3280∗∗∗	No activity
LHR-AA	16,650 ± 2700∗∗∗	No activity
LHR-AAA	11,800 ± 4700∗	Not tested
LHR-AAAA	14,690 ± 4220∗∗	Not tested

The IC₅₀ values listed are the mean ± SD co-factor activity (in pM) of three independent experiments, shown graphically in Figure 3. Statistically significant differences for LHR-A domain variant IC₅₀ values compared to LHR-ABC/CSL040 were calculated by an unpaired t test; ∗ p < 0.05; ∗∗ p < 0.005; and ∗∗∗ p < 0.0005.

CR1, complement receptor 1; LHR, long homologous repeat.