Changes in IgE, IgE Bet v 1 and IgG4 levels after successful allergen-specific therapy with a sublingual birch preparation

Evaluation of clinical effect is used as a marker of efficiency in patients wwith allergic rhinitis (AR) subjected to allergen-specific immunotherapy (AIT). This assessment is subjective and may be influenced by individual perception, expectations, and fluctuations in pollen concentrations. Therefore, development of objective markers is necessary to monitor therapy outcomes. A single-center, cross-sectional study was conducted in 26 patients with AR sensitized to birch, having been divided in two groups: those who had not yet received ASIT (AIT0) and those who had completed two courses of treatment (AIT2). The treatment was performed in two courses of birch allergy immunotherapy with the Staloral allergen, administered for, at least, 5 months at a dose of 120–240 international units (IR) per day. After two courses of AIT, a significant decrease in medication usage was observed. Moreover, a marked improvement in AR severity was noted, with 85% of patients exhibiting mild grade, and only 15% experienced a moderate course of the disorder, compared to the AIT0 group (p = 0.001). The median total IgE level before therapy was 455.1 IU/mL (154.8-537.4), and after two courses of ASIT it was 136.2 IU/mL (88-484.7), p = 0.27. According to Bayesian analysis, it is likely that the total IgE will be lower after therapy, at a moderate probability (BF = 4.9). The median IgE level specific to Bet v1 before therapy was 100 kU/L (36.5-100), with high levels (> 100, beyond the range of test) detected in more than a half of the patients. Patients in the AIT+2 group had a median sIgE of 53.5 kU/L (38.8-100), p = 0.71. Bayesian analysis suggests that IgE levels decrease with a weak probability (BF = 3.4). In the total group of patients with allergic rhinitis, IgG4 Bet v1 was determined. In the group without ASIT, the median IgG4 level was 0.60 (0.16-1.0) mg/L, after ASIT, the specific IgG to birch was significantly increased to 2.16 (1.44-3.00) mg/L, p = 0.02, with moderate probability for increase (BF = 4.41). After ASIT, specific IgG to birch significantly increased to 2.16 mg/L (1.44-3.0), p = 0.02 and a moderate increase probability (BF = 4.41). ROC analysis of “IgG4 with repeated AIT course” model showed a good diagnostic potential, with AUC value of 0.87 and p = 0.018. Measurement of sIgE levels and IgG4 may be useful for assessing the efficacy of ASIT and understanding the immune changes. Further research and standardization of diagnostic technique may enhance the significance of these markers in clinical practice.