[Air pollution and biological defence (author's transl)].

Differences of individual reactivity and, therefore, in the strength of effect air pollution exerts in different subjects of a population under study, are well known. Several experimental and epidemiologic results point to the possibility that this phenomenon is due to variations in the defence mechanisms of the human body. Some important findings relating to this problem are: Deterioration of lung clearance by inhalation of NO2 or lead chloride; damage to alveolar macrophages by air borne particulates in vitro and in vivo; enhanced activation or synthesis of the C'3 complement fraction under the influence of air pollutants; higher frequency of enlarged tonsils and lymph nodes, of pathogenic bacteria on tonsillar surfaces, and of relatively lower lysozyme concentrations in children living in urban or industrialized areas; decreased resistance to infections, elicited by inhalation of O3 or a lead aerosol; immuno-suppressive effect of heavy metals and organic compounds; allergic reactions against quite a number of chemicals; detoxification and toxification, e.g. formation of ultimate carcinogens, of organic molecules; induction or inhibition of the metabolism of benzo(a)pyrene by particulate extracts or by CO, NO2, and lead, resp.; deficiency of DNA--repair in disease conditions predisposing to the development of cancer; tendency, in allergics, to a relatively lower incidence of cancer; adaptation to the effects of CO or SO2. These facts, and knowledge not cited here, are in favour of the existence of close connections between various defence mechanisms, air pollution, and its effects on the human organism.