Representative Scatchard plots of the binding of¹²⁵I human GM-CSF specific activity to bone marrow cells from patients no. 1 (A) and 2 (B) with acquired PAP and control individuals (C and D). The calculated dissociation equilibrium binding constants for the high-affinity (K_d1) and low-affinity (K_d2) sites are given along with the mean number of sites per cell (in parentheses).