['To investigate cytokine expression following irradiation of mice, predominantly in lung tissue but also in selected other tissues.', 'Mice of strain ICR were whole-body (unilaterally) exposed to 3-20 Gy of (60)Co gamma-rays. Colony-stimulating activity (CSA) of lung-conditioned media (LCM), and also other non-haemopoietic and haemopoietic organs, and blood serum of mice was assayed using a GM-CFC bioassay. The production of GM-CSF, IL-6 and TNF-alpha protein in LCM and sera was determined by an ELISA method.', 'Greatest CSA was detected in conditioned media from the lungs and was induced in a dose- and time-dependent fashion, peaking at 3-9 days after irradiation with a lethal dose of 9 Gy. Conditioned medium prepared from lungs that had been irradiated with a dose of 9 Gy in vitro did not exhibit an increase in CSA. However, whereas the lung-conditioned medium from irradiated mice was found to produce CSA, sera from normal or irradiated mice did not lead to this effect. A significant increase in CSA in sera was observed in the presence of a suboptimal concentration of IL-3, implying that they comprise the co-stimulatory activity (CoSA). The results showed that radiation exposure increased GM-CSF and TNF-alpha protein levels but did not affect IL-6 production in LCM. In contrast, IL-6 and TNF-alpha protein levels in serum were increased after irradiation but no GM-CSF production could be detected.'] Does irradiation induce increased production of haemopoietic and proinflammatory cytokines in the mouse lung?