The effect of a panel of recombinant human (rh) cytokines on the generation of human eosinophil precursors was assessed using a two-step culture technique. Normal human bone marrow was preincubated with different cytokine combinations in liquid culture before assessment of the number of eosinophil progenitors, which give rise to eosinophil colony-forming units (CFU-Eo) on secondary semi-solid c...