The relationship between autoimmunity and specific immunotherapy for allergic diseases.

The aim of this study was to perform a 20-year post-specific immunotherapy (SIT) observational evaluation for an assessment of any manifestations of autoimmune disease or the appearance of autoantibodies in serum. In total, 1,888 patients (902 women and 986 men) were observed. The mean age of the patients was 34.1 ± 12.4 y at the start of the prospective observation after finishing SIT. New incidences of autoimmune disease and/or the presence of autoantibodies in serum were monitored. The SIT group was compared with control groups consisting of allergic patients who had very received SIT and with non-allergic subjects. There were no significant differences in the autoimmune disease prevalence between the allergic patients with or without SIT. However, significantly higher prevalence of 4 different autoimmune diseases (AID) were observed in the non-allergic patients during the same period. Additionally, the incidence of 8 different autoantibodies was significantly higher in non-allergic patients than in control subjects. Hashimoto disease was the most common autoimmune disease observed. The results of this long-term observational study indicated a lack of a significant prevalence of new instances of autoimmune disease during 20 y of observation post-SIT and at a rate lower than that of non-allergic control subjects, suggesting that SIT is safe in this regard in the long term.