We have studied the tissue distribution of interleukin (IL) and hemopoietic colony-stimulating factor (CSF) transcripts in mice by S1-nuclease protection analysis. Accumulation of several of these mRNAs in response to intravenous injection of lipopolysaccharide (LPS) appears to occur in a tissue-specific fashion. IL-1 alpha transcripts accumulate in spleen and lung; IL-6 transcripts accumulate in kidney, heart, and spleen; granulocyte-macrophage-CSF transcripts accumulate in lung and heart; and granulocyte-CSF transcripts accumulate in heart. Three distinct patterns of in vivo mRNA accumulation were detected: 1) silent--interleukins 2-5 showed no transcripts in either LPS-treated or untreated animals; 2) induced--IL-1 alpha, IL-6, granulocyte-macrophage (GM)-CSF, and G-CSF transcripts were increased in abundance in LPS-injected mice; and 3) constitutive--M-CSF transcripts were found in similar amounts in both untreated and treated mice and were present in all tissues examined.