The effect of cigarette smoke on adherence of respiratory pathogens to buccal epithelial cells

Smoking is associated with an increased risk of respiratory tract infection in adults. In children, exposure to cigarette smoke is a risk factor for r espiratory tract infection and bacterial meningitis: Active smoking and pas sive exposure to cigarette smoke is also associated a with carriage of some potentially pathogenic species of bacteria in both adults and children. Th e aims of the study were to determine the effect of active smoking on: (1) bacterial binding to epithelial cells; (2) expression of host cell antigens that act as receptors for some species; and (3) the effects of passive exp osure to water-soluble components of cigarette smoke on bacterial binding. Flow cytometry was used to assess binding to buccal epithelial cells of the following species labelled with fluorescein isothiocyanate: Neisseria meni ngitidis, Neisseria lactamica, Streptococcus pneumoniae, Bordetella pertuss is, Haemophilus influenzae, Moraxella catarrhalis, Staphylococcus aureus. F low cytometry was also used to assess expression of host cell antigens whic h have been identified as bacterial receptors. For each species, binding to cells of smokers was significantly higher than to cells of non-smokers; ho wever, expression of host cell antigens was similar on epithelial cells of both groups. Non-dilute cigarette smoke extract reduced binding of bacteria to epithelial cells, but dilutions between 1 in 10 and 1 in 320 enhanced b inding. We conclude that smokers might be more densely colonised by a varie ty of potentially pathogenic bacteria. The enhanced bacterial binding to ep ithelial cells of smokers is not related to enhanced expression of host cel l antigens that can act as receptors for some species, but possibly to comp onents in the smoke that alter charge or other properties of the epithelial cell surface. Passive coating of mucosal surfaces with components of cigar ette smoke might enhance binding of potentially pathogenic bacteria. (C) 19 99 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.