Relationship between soluble HLA-G and HLA-A,-B,-C serum levels, and interferon-γ production after sublingual immunotherapy in patients with allergic rhinitis

Allergic rhinitis (AR) is characterized by a T-helper (Th)-2 (Th2) polarized immune response. Soluble human leukocyte antigen (sHLA) molecules play an immunomodulatory role. Specific immunotherapy is the only causal treatment for AR and is able to shift the immune response to Th1 polarization. The aim of this study was to evaluate the relationship between sHLA-G and sHLA-A,-B,-C serum levels and interferon-gamma (IFN-gamma) production in AR patients with pollen allergy before and after a preseasonal course of sublingual immunotherapy (SLIT). A total of 40 AR patients with pollen allergy were enrolled and given a course of preseasonal SLIT for 3 months. Serum sHLA-G and sHLA-A,-B,-C levels were determined by enzyme-linked immunoabsorbent assay, and cell production of IFN-gamma was evaluated by enzyme-linked immunoabsorbent spot assay at baseline and 3 months after the end of the SLIT course. There was a significant relationship between sHLA-G serum level change and IFN-gamma increase as well as between sHLA-A,-B,-C level change and IFN-gamma increase after SLIT. The present study provides the first published evidence that the reduction of sHLA molecules serum levels and the increased IFN-gamma production after SLIT in AR patients with pollen allergy are significantly related phenomena.