We have previously described that hydrated pollen grains and their allergenic extracts possess intrinsic NAD(P)H oxidase activity, which catalyzes the production of reactive oxygen species (ROS) and induces oxidative stress in the lung or conjunctiva. This oxidative insult promotes the development of adaptive immune responses against innocuous pollen proteins and augments allergic airway inflammation induced by pollen antigens. In this study we investigated the ROS-producing activity of short ragweed (Ambrosia artemisiifolia) pollen extract (RWE) in detail. First, we found that in the presence of NADPH, RWE produces more ROS than after addition of NADH. An in situ nitroblue tetrazolium assay demonstrated that at least two distinct enzymes are responsible for ROS generation in RWE. The first one can use both NADPH and NADH as substrates, while the second one produces ROS only in the presence of NADPH. We observed that despite the fact that sera from non-allergic individuals have lower non-enzymatic antioxidant capacity, they exhibit higher efficacy in inhibition of ROS generation by RWE compared to sera from allergic patients. Western blot analysis revealed that antibodies against some pollen proteins associated with ROS production of RWE are present only in the sera of non-allergic subjects. Our novel findings raise the possibility that these antibodies may be able to block the ROS production by pollen enzymes hereby prevent the sensitization of non-allergic individuals.
- Copyright © 2013 by The American Association of Immunologists, Inc.