Interleukin (IL1 to IL7) gene expression in fetal liver and bone marrow stromal clones: cytokine-mediated positive and negative regulation.

Mouse bone marrow and fetal liver stromal clones have been analyzed for their cytokine mRNA expression. The reverse transcriptase polymerase chain reaction (RT-PCR) has allowed us to detect interleukin (IL) mRNA levels, even if synthesized at levels not detectable by Northern blot analysis. We found that stromal cells possess the potential to constitutively express a much larger number of interleukins than previously described. The three stromal clones analyzed here expressed mRNA for IL3 and IL2, in addition to mRNA for IL1, IL4, IL6, and IL7. None of the stromal clones synthesized IL5 mRNA. Cytokine mRNA synthesis by stromal cells was found to be subjected to negative and positive regulation by interleukins. IL2, IL3, IL6, and IL7 gene expression was much more sensitive to cytokine regulation than that of IL1 and IL4.