BONE-MARROW AND SPLENIC GRANULOCYTE-MACROPHAGE COLONY-STIMULATING FACTOR AND TRANSFORMING GROWTH-FACTOR-BETA MESSENGER-RNA LEVELS IN IRRADIATED MICE

The effects of a myeloablative sublethal 775 cGy Co-60 gamma radiation exposure on endogenous bone marrow (BM) and splenic granulocyte-macro phage colony-stimulating factor (GM-CSF) and transforming growth facto r-beta (TGF-beta) mRNA levels were assayed in B6D2F1 female mice. BM a nd spleen were harvested from normal mice and irradiated mice on days 2, 4, 7, 10, and 14 after exposure. Cytokine mRNA levels were determin ed using reverse transcription-polymerase chain reaction, After irradi ation, GM-CSF mRNA levels were significantly increased in the BM from days 2 to 10 and in the spleen from days 4 to 10. However, when BM and splenic GM-CSF protein levels were measured using Western dot blot, n o increased protein levels were detected. Serum GM-CSF levels were lik ewise unchanged. Radiation exposure did not affect BM or splenic TGF-b eta mRNA levels and this cytokine is known to be produced by cell popu lations similar to those that produce GM-CSF. These data suggest that radiation injury to hemopoietic tissues results in differential effect s on GM-CSF and TGF-beta mRNA levels and that, in the case of GM-CSF, increased mRNA levels are not matched by increased protein production. This is a US government work. There are no restrictions on ifs use.