Allergen immunotherapy is a treatment method for Japanese cedar pollen allergy (JCPA). Patients suffer symptoms such as runny noses and itchy eyes in pollen season often early spring in Japan. In the therapy, patients take in a small amount of pollen extract dose for several years and their allergic symptoms are suppressed when exposed to large amount of environmental pollen. However, the therapy is not always effective for all the patients of JCPA.
To reveal conditions in which the therapy is effective, we developed simple mathematical model of allergen immunotherapy describing the differentiation process of Th2 cells (type 2 helper T cells; trigger of allergy) and Treg cells (regulatory T cells; suppressor of allergy). We found conditions for therapeutic success as follows:  Treg cells must have a low decay rate in order to achieve accumulation during therapy phase, and  therapy schedule with a longer "induction phase" in which patients have gradually increasing pollen dose with time is more effective in suppressing allergy by exposure to environmental pollen without symptoms caused by the therapy itself.
Recently, close relation between human immune system and intestinal microbes has been known, and the effect of a particular group of bacteria on avoiding development of allergy has been reported. In this seminar, I will discuss a possible extension of the allergen immunotherapy model to a coupled immune-enterobacteria dynamics.