Results from animal experiments as well as from epidemiological studies of exposed workers show that the immune system sensitively responds to xenobiotics. In connection with outdoor air pollution as it is found in industrial and densely populated areas, alterations of the immune response were demo;nstrated by an enstrated by an enhanced complement activation in former studies. The survey presented here involved 1283 women living in five cities in the region of Cologne/Dusseldorf (polluted areas, n = 6) and the reference area, Borken. The serum concentratons of several parameters of the humoral immune defence (IgA, IgG, IgM, IgE, and C3c) were determined. After adjusting for confounders (questionnaire data) significantly higher percentages of serum C3c-concentrations above the norm were found in five of the six index areas. Percentages of IgA-concentrations above the norm were higher in all index areas compared with the reference area. In some areas the percentages of IgM- and IgG-concentrations above the norm markedly exceeded those from Borken. The same holds for the proportion of women with at least three parameters' concentrations above the norm. The highest proportion of IgE-values above the norm was found in the central part of Cologne, an area with highly traffic-related air pollution.
