Scatchard transformation of representative binding data. (A) COS cells transfected with IL-3Rα + hβc showing two site binding kinetics with a mean high-affinity kd of 80 pmol/L (n = 6, P < .001). (B) COS cells transfected with IL-3RΔNT + hβc also showing two site binding kinetics, but with a 14-fold decreased mean high-affinity kd of 1,146 pmol/L (n = 4, P < .001). (C) FDC-P1 cells stably expressing IL-3RαΔCT + hβc (high-affinity kd of 224 pmol/L). (D) FDC-P1 cells stably expressing IL-3RαΔNT + hβc (high-affinity kd of 1,600 pmol/L). Data points are the means of duplicates.