Abstract
OBJECTIVE: This review discusses the current state of immunotherapy and how the CD4 T-cell response is pivotal in altering the allergic response. DATA SOURCES: PubMed literature review. STUDY SELECTIONS: Articles pertaining to subcutaneous, sublingual, and oral immunotherapies, with specific emphasis on those describing the T-cell response. RESULTS: Although many drugs are available that help ameliorate allergic symptoms, the only intervention that has proved to provide long-term benefit and modulation of disease is immunotherapy. Many routes of immunotherapy are being pursued, including subcutaneous, sublingual, and oral immunotherapies; however, subcutaneous immunotherapy has the historical record of leading to immune changes that alter the immune response at subsequent allergen exposure. These changes are mediated by the induction of peripherally derived T-regulatory cells and appear to occur only after high-dose therapy for 3 to 5 years. Newer methods of sublingual and oral immunotherapies are currently being investigated, but their efficacy is not yet on par with subcutaneous immunotherapy. CONCLUSION: The primary cells ultimately responsible for successful immunomodulation are CD4 T cells, specifically peripherally derived T-regulatory cells.