Immune and inflammatory function in cigarette smokers.

Abstract

Immune and inflammatory function in cigarette smokersTobacco smoking is associated with increased prevalence of various diseases, both in the respiratory tract and in distal organs.The possibility that tobacco smoke induced changes in immune and inflammatory processes may play a part in the aetiology and pathogenesis of many of these diseases was first recognised in the mid 1960s.The ensuing decade witnessed a steadily increasing research effort centred on toxico- logical aspects of chronic inhalation of tobacco smoke in relation to immune and inflammatory cell function in experimental animals.This work (reviewed by Holt and Keast') defined a discrete pat- tern of change in animals during the course of tobacco smoke exposure, with the following salient features: (1) systemically, biphasic fluctuations were observed in primary T cell dependent humoral and cellular immune responses, initial enhancement dur- ing the first few months of exposure eventually giving way to suppression in chronically exposed animals;(2) T cell independent immune responses (for exam- ple, to bacterial polysaccharide antigens) and second- ary immune responses dependent on T memory cells remained normal in these animals; (3) an immediate and profound suppression of T cell function was noted in the respiratory tract, together with (4) the steady development of an expanded and functionally altered population of alveolar macrophages.Recognition of the possibility that similar effects occur in man has provided the impetus for various direct studies on aspects of immune and inflammatory cell functions in human smokers.Fur- thermore, it has become accepted practice to segre- gate the smokers within "control" populations, par- ticularly in studies using bronchoalveolar lavage.The available data from these human studies are reviewed below in the light of the information available from earlier animal experiments. Studies on peripheral blood CELL POPULATIONSThe phenomenon of smokers' leucocytosis, character-