Antigenic activity of nonpollen parts (leaves and stems) of allergenic plants (Parietaria judaica and Dactylis glomerata).

In patients with respiratory allergy to pollen it is common to correlate the onset, duration and intensity of clinical symptoms with the count of atmospheric allergenic pollen grains. Pollen counts, however, may not reflect the total airborne allergen exposure since previous data suggest that pollen allergens may also be carried in microaerosol suspensions. These microdroplets may penetrate deeply into the airways, where pollen grains are too large to penetrate, eventually inducing asthma. The origin of these allergenic aerosols is still uncertain. We investigated whether antigenic activity is present in vegetative parts of allergenic plants. We have used extracts from leaves and stems of Parietaria judaica and Dactylis glomerata to evaluate patients with allergic sensitization to pollen allergens of these plants (19 grass-sensitive patients and 23 Parietaria sensitive). By using skin prick testing and RAST to stem and leaf extracts other than pollen extracts we observed that most patients sensitive to grass or Parietaria pollen had small responses to extracts of stem or leaf. We conclude that allergenic components are present throughout most of Parietaria judaica and Dactylis glomerata plants, most highly concentrated in the pollen but present in the leaves with a trace in the stems.