Comparison of IgE induction in mice by pollens from three pine tree species

Background Over the years, pine pollens have been excluded as an allergen due to its relatively large size, low protein content, and waxy hydrophobic layer, despite their abundance. However, recent studies suggest the possibilities of pine pollens being allergens, and it has been reported that allergy symptoms were highly prevalent in areas with considerably large pine forests and high possibility of exposure to the pollen. Therefore, we conducted a comparative analysis of the allergenicities of the pollens from the dominant species of Korean pines, red pine (Pinus densiflora), black pine (Pinus thunbergii), and pitch pine (Pinus rigida), in mice. Methods The protein composition of the pollens from the three pine species was compared via sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The pine pollens and proteins extracted from the pollens were introduced to BALB/c mice by nasal inhalation and application to exposed skin and the IgE produced by the mice were extracted from blood and analyzed via ELISA. Results SDS-PAGE showed differing protein compositions of the pollens of the three pine species. Analysis of blood IgE compositions showed a similar amount of IgE produced when pollens were applied to skin. In contrast, when mice inhaled the pollens, P. densiflora was shown to induce significantly more IgE production than those of the other two species. Conclusions The experimental results demonstrate that the pollens of all three South Korean pine species induce IgE production, and this production was more pronounced when the pollens were inhaled than when they were applied to the skin. Of the three species, the pollen of P. densiflora was found to induce the highest level of IgE production.