In vitro culture of circulating CFUEOS from normal donors.

Using an accurate technique for staining and scoring soft agar cultures, this study defines the incidence of circulating CFUEOS in normal donors. With whole mononuclear cells as the source of colony stimulating factor (CSF) and fetal calf serum, 49.6% +/- 3.5 of the colonies were eosinophilic; with human placental conditioned media and fetal calf serum 33.2% +/- 12.9 of the colonies were eosinophilic, with AB serum and whole mononuclear cells in the feeder layer 58.6% +/- 9.1 of the colonies were eosinophilic. The percentage of mixed neutrophil/eosinophil colonies was similar under varying culture conditions suggesting the presence of circulating progenitor cells capable of producing both lines.