Leukocyte recruitment to airways by aldehyde-carbon combinations that mimic cigarette smoke

Exposure of Syrian golden hamsters to formaldehyde (3 to 250 p.p.m.) evaporated onto carbon (21 to 805 mg. per cu. m.) recruited polymorphonuclear (PMN) leukocytes to the epithelium of tracheas and intrapulmonary airways which peaked at 24 to 48 hours. Acrolein (less than 6 p.p.m.) on carbon (593 mg. per cu. m.) caused PMN recruitment which was maximal at 12 hours. The vapor phase of cigarette smoke produced PMN leukocyte recruitment of the same magnitude and with the same time course. In contrast, exposure to formaldehyde at doses of 2 to 250 p.p.m. and acrolein at 6 p.p.m. was cytotoxic to airway cells and caused prompt and delayed exfoliation but no recruitment of PMN leukocytes. There was no difference in cytotoxicity when carbon was present. Leukocyte recruitment occurred only when carbon was present, either given simultaneously wiht aldehydes or with adsorbed aldehydes. Thus, aldehyde vapor simulates the cytotoxic effects of particle-free cigarette smoke vapor. Of greater significance is the finding that an aldehyde, formaldehyde or acrolein, inhaled adsorbed on carbon or simultaneously with carbon to hamster airways is chemotactic for PMN leukocytes just as is the vapor phase of cigarette smoke when given simultaneously with carbon particles.