Decreased FOXP3 mRNA expression in children with atopic asthma and IgE-mediated food allergy.

Background: The role of T regulatory lymphocytes has been investigated in various allergic diseases. However, the precise relation between the phenotype and severity of allergic diseases and the changes in FOXP3 mRNA expression are not fully understood.

Objective: To compare the expression of FOXP3 mRNA in children with asthma with and without concomitant food allergy (FA) with healthy children and children with only FA.

Methods: The study included 82 children: 15 with atopic asthma and IgE-dependent FA, 27 with atopic asthma without FA, 20 with IgE-dependent FA without asthma, and 20 healthy children without atopy. Reverse transcription was performed using a commercially available High Capacity cDNA Archive Kit (Applied Biosystems, Carlsbad, California). Analysis was carried out with a 7900HT real-time polymerase chain reaction system (Applied Biosystems).

Results: The average level of the FOXP3 gene expression in children with allergy was significantly lower compared with healthy children (2.2 ± 1.3 vs 4.2 ± 4.2; P = .014). The lowest mean level of FOXP3 mRNA expression (1.9 ± 1.6) was recorded in children with asthma and FA, and the highest level (4.2 ± 4.2) was recorded in healthy children without atopy (P = .036). A milder course of asthma or the degree of allergic reaction after a food challenge was associated with higher FOXP3 mRNA expression.

Conclusion: Significantly lower levels of FOXP3 gene expression, observed more commonly in children with asthma and IgE-dependent FA than in healthy controls, were associated with a more severe clinical course. Therefore, FOXP3 expression could serve as an indicator of severe asthma with concomitant atopic conditions such as IgE-dependent FA.