IL-3-induced coexpression of histidine decarboxylase, IL-4 and IL-6 mRNA by murine basophil precursors

Murine low-density bone marrow cells sorted from the blast cell window on t he basis of high rhodamine-123 retention (Rh-bright), are highly enriched i n histamine-, IL-4-, and IL-6-producing cells. We established by in situ hy bridization that up to 50% of this population (around 0.25% of the whole bo ne marrow) coexpressed the transcripts for these molecules upon stimulation with IL-3, Rh-bright cells were also positive for mRNA encoding the alpha, beta, and gamma chains of the Fc(epsilon)RI which was functional since agg regated IgE induced the same percentage of cells hybridizing With the HDC p robe as IL-3, Clonogenic progenitors and histamine- and cytokine-producing cells copurified in the Ph-bright population, but could be distinguished by their c-kit expression, CFU-C being more frequent in the c-kit(high) fract ion, while histamine and IL-6 producers were enriched in the kit(low) count erpart. Ultrastructural analysis of Ph-bright cells revealed essentially tw o subsets, namely undifferentiated blast cells and basophil precursors, No other lineage-committed population was enriched by this sorting procedure, and it can therefore be concluded that coexpression of HDC, IL-6, and IL-4 transcripts in response to IL-3 or aggregated IgE takes place mainly in hem atopoietic precursors belonging to the basophil lineage. (C) 1999 Internati onal Society for Experimental Hematology. Published by Elsevier Science Inc .