Figure 3.

Representative Scatchard plot of [³H]NECA saturation binding data. Competition binding experiments were performed, incubating aliquots of neutrophil membranes with 20 nmol/l [³H]NECA and different NECA concentrations (50 nmol/l to 2 mmol/l), in the presence of 50 nmol/l CPA and 100 nmol/l SCH₅₈₂₆₁. Empty circles indicate neutrophil membranes from healthy volunteers (affinity constant [Kd] = 476 ± 34 nmol/l, maximum number of binding sites [B_max] = 3696 ± 210 fmol/mg); filled circles indicate neutrophil membranes from systemic sclerosis (SSc) patients overall (Kd = 469 ± 35 nmol/l, B_max = 1292 ± 98 fmol/mg). Assays were performed in triplicate.