APOPTOSIS AND FAS FAS LIGAND MESSENGER-RNA EXPRESSION IN ACUTE IMMUNE-COMPLEX ALVEOLITIS IN MICE/

Deoxyribonucleic acid (DNA) strand breaks as a characteristic of apopt osis, and Fas antigen (Fas)/Fas ligand (Fast) expression may participa te in acute immune complex alveolitis in mice. Male Institute for Canc er Research (ICR) mice were injected intravenously with immunoglobulin C (IgG) antibodies against ovalbumin and inhaled an aerosolized oval albumin (OA) solution, They were killed at 4, 6, 12, 24, 48 h and 7 da ys after aerosolization, We assessed DNA fragmentation by agarose gel electrophoresis and terminal deoxynucleotidyl transferase-mediated deo xyuridine triphosphate biotin nick end-labelling (TUNEL), The expressi on of Fas and Fast messenger ribonucleic acid (mRNA) in lung tissues w as assessed by reverse transcriptase (RT) polymerase chain reaction, a nd by in situ hybridization (ISH) to localize Fas mRNA, and RT in situ polymerase chain reaction to localize Fast mRNA.The fragmentation of DNA extracted from lung tissue was found 6-24 h after OA inhalation. T UNEL detected positive signals in bronchial and alveolar epithelial, e ndothelial and inflammatory cells in the lung tissue, These positive s ignals had disappeared 7 days after OA inhalation. TUNEL also detected positive signals in apoptotic neutrophils in bronchoalveolar lavage f luid at 6-12 h, Fas mRNA was expressed in the alveolar epithelial and inflammatory cells, while the expression of Fast mRNA appeared to be u pregulated in infiltrating inflammatory cells at 6-24 h. These results suggest that apoptosis may be associated with the resolution of infla mmation and with tissue repair and also suggest the involvement of the Fas antigen/Fas ligand pathway in acute immune complex alveolitis in mice.