Ambient pollutants as adjuvant for allergic sensitization: the emerging role of platinum group elements

The prevalence of asthma and allergies often observed in urban metropolitan areas as compared to rural and farm communities is still an enigma. Westernized life styles, type of farming and exposure to environmental pollutants seem to simultaneously interact in the determination of this phenotype in genetically predisposed individuals. In this scenario, we asked whether and to what extent we could single out antropogenic airborne contaminants in general, and platinum group elements in particular as relevant causal factors in the generation and in the clinical expression of allergic immune responses in exposed individuals. To this aim, we evaluated epidemiological and basic immunology studies published on peer-reviewed journals indexed in Medline on this subject. We reviewed studies focused on effect of the exposure to platinum group elements on the allergic immune response, with specific reference to our own studies, on their influence on dendritic cells and on the consequent skewing of T-helper and T-regulatory lymphocyte functions. Our laboratory contributed to generate consistent evidence supporting the notion that anthropogenic emissions in general, and platinum group elements in particular, can functionally modulate the immune response in a coordinated pro-allergic fashion. We conclude that in genetically predisposed individuals platinum group elements exert an adjuvant effect specifically leading to more severe allergic reactions.