Although various mechanisms involving antibodies and various cell types participate, a Thl and Th2 cells imbalance seems to play a central role for allergy development. Other lymphocyte subpopulations, such as Th17, CD4 FOXP3, and Th9 positive regulatory T lymphocytes may also be involved in the allergic response. Regulatory processes are an appealing target for therapeutic approaches aiming to solve allergic reactions by restoring the delicate balance within the immune system. Transfer factor (TF) or dialyzable leukocyte extract is meant to transfer cell-mediated immunity from immune competent donors to unsensitized or deficient recipients. A PubMed search on the current knowledge on TF indicates that TF may restore the Th1/Th2 balance and improve immune regulatory mechanisms of patients receiving it. Our preliminary results demonstrate that TF induces mRNA expression of IFN-g, osteopontin, RANTES, and hBD-2 in human healthy subjects. TF has been used to treat a variety of immune dysfunction related-pathologies, such as allergy, autoimmunity, immunodeficiencies, infectious diseases and tumors. Patients receiving TF together with their conventional treatment often have better clinical evolution than without it, as we have witnessed, adding TF to the usual medical treatment of allergic diseases as an attempt to provide allergic patients with those regulatory elements that they apparently lack but require to achieve properly regulated immune responses and thus obtain a faster and better resolution of allergic reactions.