Influence of allergen-specific immunotherapy on IL-4-dependent IL-12 production by monocytes

Allergen-specific immunotherapy (AIT) is an effective method of allergy treatment. Reduction of allergy symptoms followed by AIT presumably depends on modification of cytokine production, especially of IFN-γ and/or IL-4. Previously, we found that lower IL-12 production by allergic monocytes than in healthy control, could depend on higher IL-4 receptor α-chain (CD124) expression. Since IFN-γ production is stimulated by IL-12, which in turn is down-regulated by IL-4, the aim of study was to analyze the influence of AIT on the network of these cytokines. Moreover, we estimated the possible role of CD124 in that process. Patients (n=16) with grass pollen allergy were subjected to AIT with Allergovit for 5 to 6 weeks. The clinical examination and blood analyses were performed before and after AIT. Clinical improvement in course of AIT was rather weak, however, we found significant increase of mean IFN-γ production by PBMC. Although the increase of mean IL-12 production by monocytes following AIT was non-significant, we observed statistically significant decrease of monocyte sensitivity to IL-4 suppressed IL-12 production. Flow cytometry analysis revealed significant decrease of CD124 expression on monocytes after AIT. Despite unchanged mean IL-4 level the decrease of CD124 expression after AIT could explain the decreased monocyte sensitivity to IL-4 and its role in further IL-12 and IFN-γ tuning.