Human alpha-1-proteinase inhibitor is inactivated by exposure to sidestream cigarette smoke.

Direct exposure of human alpha-1-proteinase inhibitor (alpha 1PI) to sidestream cigarette smoke causes an initial, rapid loss of elastase inhibitory capacity followed by a slow, gradual loss of activity as the protein is incubated in the smoke-exposed aqueous buffer solution. The exposure used here gives a total of 40% inactivation using one cigarette. This biphasic pattern of inactivation is similar to the inactivation seen following the direct exposure of alpha 1PI to mainstream smoke. We suggest that although exposures to sidestream smoke by nonsmokers are generally lower than the exposures to mainstream smoke experienced by smokers, sidestream smoke has the potential to produce similar types of damage as mainstream smoke, including emphysema-like damage, and should not be regarded as innocuous.