EFFECTS OF IL-2 TREATMENT ON DIFFERENT COMPARTMENTS OF THE IRRADIATEDRAT LUNG ANALYZED BY BRONCHOALVEOLAR LAVAGE AND LUNG-TISSUE MORPHOLOGY

In recent years, interleukin-2 (IL-2) has been used as an immunomodula tory agent in the treatment of various malignant tumours, However, thi s treatment has been limited by serious side-effects, including toxic reactions in the lung, The effects of IL-2 treatment on inflammatory c ell populations in the normal and irradiated rat lung were investigate d in this study. IL-2 was continuously administered as a subcutaneous infusion over a 6 week University Hospital Trondheim study period, Irr adiation was given in a single dose (25 Gy) the day after starting IL- 2 treatment, Evaluation with bronchoalveolar lavage fluid (BALF) analy sis and lung tissue morphology was made 6 weeks after irradiation. In nonirradiated rats, IL-2 treatment induced significant increases in th e total number of inflammatory cells in the perivascular, interstitial and peribronchial tissues as well as in the alveolar space, These inc reases were not reflected in BALF; on the contrary, a significant decr ease of the total numbers of inflammatory cells was found in BALF. Irr adiation alone caused a more pronounced inflammatory response with sig nificant increases of all inflammatory cells in all lung compartments, which was also reflected in BALF. Concomitant treatment with IL-2 and irradiation induced an enhanced accumulation of inflammatory cells in the perivascular and peribronchial tissues compared with irradiation atone. Thus, both irradiation and IL-2 treatment induce inflammatory r eactions in the lung, but there were few signs of synergistic effects seen in this study, Furthermore, the results also emphasize the diffic ulties in making sophisticated conclusions from BALF analyses alone.