Cross-reactivity between Parietaria Judaica and Parietaria officinalis in immunotherapy extracts for the treatment of allergy to Parietaria

Abstract

Parietaria judaica and P officinalis are the two most common subspecies of the Parietaria genus. P judaica and P officinalis have exhibited cross-reactivity in previous studies. P. judaica pollen is the main cause of allergy in the Mediterranean area. It has been shown that a high percentage of patients sensitized to P. judaica with allergic rhinitis (AR) have an increased risk of developing asthma. The present study aimed to confirm the cross-reactivity between P. judaica and P officinalis and to evaluate the use of a single P officinalis extract in patients allergic to both subspecies as a preferable option for the diagnosis and treatment of allergy in a highly pollinated area of the Spanish Mediterranean coast. The present study was a single centre, observational cross-sectional study of adult patients diagnosed with AR and/or bronchial asthma who were sensitized to Parietaria pollen. A total of 24 patients were enrolled in the study and included in the analysis. Allergovit® immunotherapy extracts were selected for the study based on the protein content (P officinalis pollen extract). The results of an in vitro ELISA revealed that 79.1% (n=19) of the patient sera were reactive to immunotherapy extracts. ELISA inhibition assay of the IgE binding to P officinalis demonstrated inhibition values >70% in the sera of highly reactive patients, confirming the cross-reactivity between the two Parietaria subspecies. In addition, all patients enrolled in the study exhibited double skin positivity against P judaica and P officinalis extracts, as assessed by the skin prick test, further supporting the in vivo reactivity between the two subspecies. The present study demonstrated that P. judaica and P officinalis pollen extracts were highly cross-reactive, and that a unique P officinalis pollen extract may be used for the diagnosis and immunotherapy of patients allergic to Parietaria.