Immunotherapy with an extract of Olea europaea quantified in mass units. Evaluation of the safety and efficacy after one year of treatment

Abstract

Sensitization to olive pollen is a frequent cause of rhinoconjunctivitis (RC) and bronchial asthma (BA) in the region of Jaén (southern Spain), where this allergen reaches atmospheric levels of almost 7000 grains/m3 during pollen season (May and June) and produces high morbidity. Specific immunotherapy (SIT) has proven very efficient in allergic RC and BA caused by grass pollen. Considering the availability of a biologically standardized extract of Olea europaea, with its major allergen quantified in mass units, we decided to investigate SIT with this extract in a group of rhinitic and/or asthmatic patients monosensitized to olive. We studied tolerance, safety, and efficacy by comparison of the active group (subjected to SIT) with a control group that did not receive SIT. A hyposensitizing dose of Olea europaea extract was administered preseasonally, establishing a maintenance dose 3.8 times higher than those administered in conventional treatments. Eighty-three percent of the patients reached the proposed maximal dose of 75 BU, equivalent to 45 micrograms Ole e 1, with a rate of 0.8% of systemic reactions. A significant decrease in cutaneous (p < 0.001) and bronchial (p < 0.001) reactivity was observed in the active group, but not in the control group. Also, a decrease in specific IgE and an increase in IgG1 and IgG4 were found in the group of patients treated with SIT. Regarding clinical evolution, the active group, but not the control group, experienced a clear statistically significant improvement both in nasal (p < 0.05) and bronchial (p < 0.05) symptoms, in addition to a significant decrease in the consumption of antihistamines (p < 0.05) and beta 2-agonists (p < 0.01). In conclusion, SIT with olive extract proved to be safe and efficacious for the treatment of asthma and rhinitis caused by this allergen.