Adjuvant Effect of Cadmium on Pollen Grain Allergenicity in Petunia hybrida Juss

 Cadmium (Cd) is a heavy metal and an important part of diesel exhaust particles (DEPs). Cadmium in high concentrations exhibits detrimental effects and increases the allergenicity of pollen grains.

 The research aimed to study the effects of Cd on the proteins and allergenicity of Petunia hybrida pollen.

 Petunia plants were cultured in a greenhouse and treated with various concentrations of cadmium chloride (CdCl2) (400, 800, and 1200 μmol/L). The pollen was collected daily from the flowers of both experimental and control plants. Pollen extracts were prepared in phosphate-buffered saline (PBS) from control and Cd-treated plants, and changes in protein banding profiles were compared by sodium dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Mice were sensitized by the treatment of pollen extracts and aluminum hydroxide (Al(OH)3) as an adjuvant 3 times. The allergenicity of pollen extracts was evaluated by the skin test and the amount of immunoglobulin E (IgE) in the experimental animals.

 The gel electrophoresis results revealed that in the Cd-treated pollen grains, two new protein bands, 46 and 51 kilodaltons (kDa), were observed that may have allergenicity. The results of serological tests showed that the mean of wheal diameter and IgE level were higher in animals sensitized by Cd-treated pollen grains than in control ones.

 In recent years, pollinosis has increased in polluted areas, especially DEP-polluted areas; the reason may be that Cd, as an important part of DEP, acts as an effective agent in the induction of the formation of detoxifying proteins which can also act as new allergens.