Covalent binding of o,p'-DDD in rabbit lung and isolated rabbit lung cells

The irreversible binding of o,p'-DDD was examined in isolated lung cells, in lung microsomes and in vivo in male New Zealand White rabbits. Non-ciliated bronchiolar (Clara) cells had the highest capacity to bind o,p'-DDD, followed by alveolar type II cells. A fraction of mixed unidentified lung cells was also able to bind o,p'-DDD while no binding was observed in alveolar macrophages. The activation of o,p'-DDD was shown to be mediated by cytochrome P-450 in both lung microsomes and isolated lung cells. In vivo, the binding was preferentially localized in the lung alveolar and bronchiolar regions. The binding of o,p'-DDD observed in vivo may thus be caused by the capacity of several cell types to activate o,p'-DDD.