Comparison of efficacy, safety and immunologic effects of subcutaneous and sublingual immunotherapy in birch pollinosis: a randomized study

Sublingual immunotherapy (SLIT) is currently considered a valid option to subcutaneous immunotherapy (SCIT), but only a few studies made a direct comparison of their effectiveness. The aim of this study was to compare the clinical and immunological effects of SCIT and SLIT in pollinosis induced by Betulaceae.

Forty-seven adult patients were randomized to receive SCIT or SLIT, performed by Betulaceae (alder, birch, and hazel) extracts from Stallergenes (Antony, France) standardized in index of reactivity (IR) with the treatment schedules proposed by the producer. The clinical effects were established by symptom-medication scores recorded during the month of March. Side effects were reported directly by the physicians for SCIT and were registered in diary cards by the patients for SLIT. Immunologic evaluation was done by measuring specific IgE and IgG4 to Bet v 1.

Thirty-four patients (19 for SCIT and 15 for SLIT) completed the registration of symptoms and drug consumption during pollen period of Betulaceae. Mean cumulative doses of respectively 50.65 IR by SCIT and 4653.1 IR by SLIT were administered, with a SLIT/SCIT ratio of 92. There was no significant difference in mean symptom-medication score between SCIT and SLIT. Systemic reactions occurred in 16% of SCIT treated but in none of SLIT treated. As to immunologic evaluation, Bet v 1 specific IgE did not rise after the pollen season in SCIT treated, while increased non significantly in SLIT treated. Bet v 1 specific IgG4 increased in both treatment, buy only the increase with SCIT was significant (p = 0.001).

SLIT and SCIT with a ratio of about 100 are equally effective in controlling rhinoconjunctivitis caused by tree pollen allergy. SLIT is safer than SCIT, but does not show the same immunologic effects on serum specific IgE and lgG4 antibodies.