Allergenic proteins in Urtica dioica, a member of the Urticaceae allergenic family.

Background: Allergy to the pollen of flowering plant species significantly affects the health of people in many parts of the world. Pollens of related genera usually share common antigens and are often, but not always, cross-reactive. Several studies have shown that Parietaria pollen is one of the most common causes of pollinosis in the Mediterranean area, whereas Urtica has no allergenic significance.

Objectives: To report on the localization of Parietaria judaica major allergen in Urtica dioica pollen grains and on the detection of allergenic proteins in U. dioica pollen grains during the hydration-activation process.

Methods: A combination of transmission electron microscopy and immunocytochemical methods was used to locate allergenic proteins in U. dioica pollen grains after different periods of hydration-activation using the anti-Par j 1 (4.1.3.) monoclonal antibody and serum samples from allergic patients.

Results: No significant labeling was noted for Parj 1 allergen after 10, 15, and 20 minutes in the walls and cytoplasm. Slight labeling was observed for allergic proteins in the walls of U. dioica after 10 minutes of hydration, and no significant labeling was found after 15 and 20 minutes of hydration.

Conclusions: Immunocytochemical methods confirmed the absence of cross-reactivity between 2 related genera, Parietaria and Urtica, and the lowest allergenic potential of U. dioica.