Long-lasting effect of a monophosphoryl lipid-adjuvanted immunotherapy to parietaria. A controlled field study.

BACKGROUND: The clinical efficacy of Monophosphoryl lipid A-adjuvanted immunotherapy (MPLA-SCIT) is ascertained, but there are no data on its possible long-lasting effect. We assessed in a real-life setting the persistence of the clinical effect five years after discontinuation.
METHODS: Patients with parietaria-induced respiratory allergy and fulfilling the criteria for immunotherapy prescription were evaluated at baseline, after the third year of MPLA-SCIT and five years after discontinuation. Visual analog scores, severity of the disease, pulmonary function and skin reactivity were assessed. Matched subjects who refused immunotherapy served as controls.
RESULTS: Twenty nine patients received MPLA-SCIT and 28 were the control group. There was a significant clinical improvement, as assessed by VAS only in the active group after 3 years that remained significant at 5 years versus baseline and controls. The distribution of severity of rhinitis was overall decreased at 3 and 8years as well. The number of patients with conjunctivitis in the active group decreased from 19 to 6 at the end of the treatment and to 9 after 5 years. There was also a decrease in the number of patients with asthma symptoms (from 6 to 2 to 4), which doubled in the control group. A significant reduction in the wheal of the Parietaria skin test was seen in the active group at the end of the treatment (9.5 +/- 2.1 mm vs. 6.4 +/- 2.6 mm; p = .01), but this reduction was lost at the 5-year. No relevant change was overall detected in pulmonary function.
CONCLUSION: MPLA-SCIT is effective, and the clinical efficacy is maintained after 5 years of discontinuation.