Pollen polarize dendritic cells

How do pollen particles provoke allergic reactions? On page 627, Traidl-Hoffmann et al. put some of the blame on bioactive lipids that are released from pollen and cause dendritic cells (DCs) to initiate a T helper 2 (Th2)-biased, allergy-promoting immune response. This response may explain in part why increased car fumes are associated with greater prevalence of allergies.

This group had discovered previously that pollen grains rapidly liberate eiconasoid-like substances, which are similar to prostaglandins and leukotrienes, when in an aqueous environment. These lipids bound to neutrophils and eosinophils (both involved in allergies and other immune reactions) and induced their activation, leading the group to propose that the release of these lipid mediators is an important event in allergic sensitization. What these data did not explain, however, was how the...