Changes in allergen specific IGG4 and ige after subcutaneous immunotherapy in children under 4 years of age

RATIONALE: Subcutaneous immunotherapy (SCIT) has been shown to increase antigen specific IgG4 levels. The immunologic response to SCIT in children under age 4 has not been prospectively studied. METHODS: In an ongoing randomized control trial of multiple allergen SCIT in atopic inner city children with asthma between the ages of 18 to 47 months, serum levels of allergen specific IgG4 and IgE were determined before and after 3 years of SCIT. A mixed effect longitudinal model was used to compare immunoglobulin levels between control group (n=11) and immunotherapy group (n=10). RESULTS: Asignificant rise in allergen specific IgG4 in response to SCIT was observed for all antigens tested (p≤0.006). The most significant responses were seen in mouse IgG4 (coefficient 8.38 ug/l, 95%CI 4.10 to 12.6 ug/l, p <0.001) and dog IgG4 levels (coefficient 3.45 ug/l, 95% CI 2.06 to 4.84 ug/l, p <0.001). In contrast, no significant changes were seen for serum specific IgE levels for most antigens. The only allergen with a statistically significant decrease in serum specific IgE in response to SCIT was cat (coefficient -10.3kU/l, 95% CI -19.1 to -1.49 kU/l, p =0.016). CONCLUSIONS: This preliminary study suggests that children who start multiple allergen SCIT between 18 months and 4 years of age can mount a significant increase in allergen specific IgG4 levels after a 3-year course of multiple allergen SCIT, including mouse antigen. A significant decrease in serum specific IgE was only seen for cat antigen.