ALVEOLAR MACROPHAGES FROM SHEEP NATURALLY INFECTED BY VISNA-MAEDI VIRUS CONTRIBUTE TO IL-8 PRODUCTION IN THE LUNG

Sheep naturally infected by visna-maedi virus often develop a chronic interstitial lung disease characterized by an alveolitis comprising ly mphocytes, neutrophils and macrophages. The alpha chemokin interleukin -8 (IL-8) was detected in cell free bronchoalveolar lavage fluid from naturally infected animals, confirmed by RT-PCR, presenting typical le sions of maedi and elevated total alveolar cell counts. No detectable IL-8 was found in the fluid obtained from uninfected animals. IL-8 con centration in alveolar fluid is correlated with alveolar neutrophil co unts. Bronchoalveolar lavage cells from infected animals were found to contain a large amount of IL-8 mRNA and may contribute to IL-8 produc tion. In situ hybridization showed that macrophages were the predomina nt cell type expressing IL-8 mRNA. Sustained production of IL-8 by alv eolar macrophages during visna-maedi infection could suffice for neutr ophil attraction to the alveoli, and may contribute to the development of lesions. (C) 1997 Elsevier Science B.V.