Dose-dependent binding of HNP-1 to intact C1q (▪), C1q collagen-like stalks (○), and C1q globular heads (•). ELISA wells were coated with 1 μg of either C1q, C1q globular heads, C1q collagen-like stalks, or BSA (▴) and incubated with increasing concentrations of HNP-1^Biotin. After incubation, bound HNP-1^Biotin was determined by subsequent incubation with streptavidin-HRP and ABTS.