Long-term allergen-specific immunotherapy correlates with long-term allergen-specific immunological tolerance

One method of treatment for allergic diseases is allergen-specific immunotherapy (SIT). The clinical efficacy of SIT in pollen-induced allergic rhinitis has been demonstrated in several controlled clinical trials. There is no consensus about the protective effect of SIT. In this study, we evaluated the correlation between the duration of SIT and relapse of allergic rhinoconjunctivitis.

We evaluated 148 patients who had received SIT between 1998 and 2006. All of the patients had allergic rhinoconjunctivitis. According to the data 116 had sensitivity to grass pollen and 32 to house dust. SIT was performed on 87 patients for 4 y (Group A) and 61 patients for 6 y (Group B).

All of the 148 patients were monitored regularly with no medication for 2 y after SIT. Thirty-one patients in Group A relapsed (36%); 11 patients in Group B relapsed (18%). Mean duration until relapse was 11.1+/-1.99 mo in Group A and 19.64+/-1.86 mo in Group B. During evaluation, symptom scores were 2.32+/-0.74 in Group A and 1.81+/-0.75 in Group B and serum total immunoglobulin E levels were 432.4+/-78.5 KU/lt in Group A and 288.6+/-55.3 KU/lt in Group B. There was significant difference between the groups (P < 0.05).

According to these results, long-term SIT therapy correlates with long-term, allergen-specific, acquired immunological tolerance.