Binding of 125I-FGF2 to immobilized PTX3. (A) PTX3-coated wells were incubated with ¹²⁵I-FGF2 in the absence (•) or in the presence (○) of anti-PTX3 antibody (5 μg/mL). (B) Wells coated with the indicated proteins (all at 440 nM) were incubated with ¹²⁵I-FGF2. (C) Wells coated with PTX3 (440 nM) were incubated with ¹²⁵I-FGF2 in the absence (–) or in the presence of the indicated unlabeled proteins (all at 111 nM; h.d. indicates heat denatured). (D) Increasing concentrations of ¹²⁵I-FGF2 were incubated onto wells coated with PTX3 (100 nM). (D, inset) Scatchard plot regression analysis of the ¹²⁵I-FGF2 binding data to immobilized PTX3. For all the experiments, bound radioactivity was measured after 2 hours at 37° C. In panels A-C, each point is the mean ± SEM of 3 to 4 determinations in duplicate, whereas the data shown in panel D represent one experiment (similar results were obtained in a second independent experiment).