Renand A, et al. - Researchers undertook this study to assess in the GRASS trial the time-course of immunologic changes during two years sublingual and subcutaneous allergen immunotherapy and for one year after treatment discontinuation. According to findings, allergen immunotherapy for 2 years was shown to be effective but was insufficient for long-term tolerance. Data showed that allergen-specific Th2 cells most closely paralleled the transient clinical outcome. Furthermore, it was likely that recurrence of the T cell ‘drivers’ of allergic immunity abrogated the potential for durable tolerance. A pro-tolerogenic mechanism may be early indicated by the persistence of IgE-blocking antibody one year after discontinuation.