Effect of complex formation with C1-inhibitor for HNP-1 binding. ELISA wells were coated with 1 μg BSA, C1-inhibitor, C1q, intact C1, or C1r/C1s. In addition, the same concentration of these proteins was coated after preincubation with 1 μg of C1-inhibitor. Subsequently, after washing, a fixed amount of HNP-1^Biotinwas added and assessed for binding. After washing, bound HNP-1^Biotin was determined by incubations with streptavidin-HRP and ABTS.