Detection of a new type of mouse eosinophil colony by Luxol-fast-blue staining

Staining with Luxol-fast-blue was shown to be a satisfactory method for identifying mouse eosinophils. IN agar cultures of mouse marrow stimulated by pokeweed mitogen-stimulated spleen conditioned medium (SCM), 2-10 compact Luxol-fast-blue positive eosinophil colonies varied according to the batch of human plasma used in the culture medium. Similar colony-forming cells were detected in the spleen and peripheral blood but not in the thymus or lymph nodes. Some Luxol-fast-blue positive eosinophil colonies were stimulated to develop by crude mouse lung conditioned medium and by high concentrations of GM-CSF purified from this source. The cells forming Luxol-fast-blue positive eosinophil colonies sedimented more rapidly (5.5-6.5 mm/h) than the cells forming dispersed-eosinophil colonies 94.5 mm/h). Transfer studies using intact colonies or redispersed colony cells failed to demonstrate an interrelationship between the two types of eosinophil colonies and the cells forming Luxol-fast-blue positive eosinophil colonies appear to be a distinct subset of eosinophil percursors.