Sublingual immunotherapy alters expression of IL-4 and its soluble and membrane-bound receptors

Seasonal allergic rhinitis (SAR) is a disease of increasing prevalence, which results from an inappropriate T helper cell, type 2 (Th2) response to pollen. Specific immunotherapy (SIT) involves repeated treatment with small doses of pollen and can result in complete and lasting reversal of SAR. Here, we assayed the key Th2 cytokine, IL-4, and its soluble and membrane-bound receptor in patients with SAR before and after SIT. Using allergen-challenge assays, we found that SIT treatment decreased IL-4 cytokine levels, as previously reported. We also observed a significant decrease in the IL-4 membrane-bound receptor (mIL4R) at the level of both mRNA and protein. SIT treatment resulted in a significant increase in the inhibitory soluble IL-4 receptor (sIL4R). Reciprocal changes in mIL4R and sIL4R were also observed in patient serum. Altered mIL4R and sIL4R is a novel explanation for the positive effects of immunotherapy with potential basic and clinical research implications.