Sublingual allergen immunotherapy (SLIT), a disease-modifying treatment for allergic rhinitis, can produce long-term therapeutic improvements through immunological responses such as the production of regulatory B (Breg) and T (Treg) cells. IL-35, the newest member of the IL-12 class, is an anti-inflammatory cytokine generated by Breg and Treg cells. There has been little research on the role of IL-35 in allergic rhinitis and during SLIT. This study covers current studies related to IL-35 and its function in SLIT. Recombinant IL-35 protein can stimulate the production of immunosuppressive IL-35-producing Breg and Treg cells. In allergic rhinitis patients, levels of IL-35 and IL-35-inducible Treg (iTR35) cells are dysregulated, which can be restored by SLIT. T cell proliferation, Th2 cytokine production, and B cell synthesis of IgE antibodies are all suppressed by IL-35-mediated tolerance to allergens.

Emerging research suggests that IL-35 and iTR35 cells may play a role in tolerance maintenance during SLIT. A deeper knowledge of the involvement of IL-35 and iTR35 cells may open up new pathways for the creation of clinical biomarkers to measure the success of allergen immunotherapy as well as innovative treatment options for allergic rhinitis.

Reference: https://journals.lww.com/co-allergy/Abstract/2019/02000/Role_of_IL_35_in_sublingual_allergen_immunotherapy.4.aspx