An improved cytochemical method for the evaluation of eosinophil colonies in soft-agar cultures from human blood or bone marrow.

A simple peroxidase staining method specific for eosinophils using 4-chloro-1-naphthol as substrate and 1,2,4-benzene triol as selective inhibitor is applied to the analysis of eosinophil colonies grown in soft-agar cultures form human blood or bone marrow. Eosinophil colonies appear strongly stained in black whereas other types of colonies (neutrophils and macrophages) remain colourless. The proposed method is easy to be performed, quick, reliable, may be associated without major problems to many other cytochemical stains and promises to be of value in hemopoiesis studies.