Detection of basophils growing in semisolid agar culture

The production of basophils in semisolid agar cultures form normal and chronic myeloid leukemia (CML) committed granulocyte-macrophage precursors was investigated using an original whole-dish staining technique with toluidine blue which produces a specific metachromasia in basophils. As additional proof of the basophilic nature of metachromatic cells, their degranulation after challenge with C5a anaphylotoxin and Synachten was observed. Our studies show that few basophils are produced in cultures form normal bone marrow. CML CFUc produce more basophils, their number being roughly correlated with the degree of basophilia. We observed only clusters composed by a pure basophilic population, while larger aggregates in which basophils could be detected were composed also by other granulocytic cells.