Generation of eosinophils from unselected bone marrow progenitors: wild-type, TLR- and eosinophil-deficient mice.

We have recently devised a culture method that generates large numbers of eosinophils at high purity from unselected BALB/c mouse bone marrow progenitors [Dyer et al., 2008. J. Immunol. 181: 4004-9]. Here we present the extended scope of this approach, as we have used this method successfully to generate eosinophil cultures of virtually 100% purity from bone marrow from C57BL/6 mice, and from TLR2, TLR3, TLR7 and TLR9-gene-deleted mouse strains on the C57BL/6 background. Both wild-type and TLR3 gene-deleted bone marrow eosinophils (bmEos) are functional, releasing peroxidase in response to the secretogogue, platelet activating factor. We have also used this method to re-evaluate production of eosinophils in bone marrow cultures from ΔdblGATA mice, a strain that is eosinophil-deficient in vivo. Interestingly, bmEos can be detected in the ΔdblGATA cultures (5% of total cells at day 10), although ~80-fold fewer bmEos are detected in ΔdblGATA than in parallel wild-type (BALB/c) bone marrow cultures. Overall, we find that generation of large numbers of eosinophils at high purity from unselected bone marrow progenitors proceeds efficiently in a variety of wild-type and gene-deleted strains, and as such this approach shows promise as a universal method for the study of eosinophil structure and function.