Adoptive transfer of tumor-specific Th2 cells eradicates tumors by triggering an in situ inflammatory immune response
Menée à l'aide de modèles murins de myélome, cette étude met en évidence des mécanismes immunitaires suggérant l'intérêt d'un traitement par transfert adoptif de lymphocytes auxiliaires Th2 spécifiques des tumeurs
Adoptive cell therapy (ACT) trials to date have focused on transfer of autologous tumor-specific cytotoxic CD8+ T cells, however, the potential of CD4+ T helper (Th) cells for ACT is gaining interest. While encouraging results have been reported with interferon-γ (IFNγ)-producing Th1 cells, tumor-specific Th2 cells have been largely neglected for ACT due to their reported tumor-promoting properties. In this study, we tested the efficacy of idiotype-specific Th2 cells for the treatment of mice with Major Histocompatibility Complex (MHC) class II-negative myeloma. Th2 ACT efficiently eradicated subcutaneous myeloma in an antigen-specific fashion. Transferred Th2 cells persisted in vivo and conferred long-lasting immunity. Cancer eradication mediated by tumor-specific Th2 cells did not require B cells, natural killer T cells, CD8+ T cells, or IFNγ. Th2 ACT was also curative against B-cell lymphoma. Upon transfer, Th2 cells induced a type 2 inflammation at the tumor site with massive infiltration of M2-type macrophages producing arginase. In vivo blockade of arginase strongly inhibited Th2 ACT, consistent with a key role of arginase and M2 macrophages in myeloma elimination by Th2 cells. These results illustrate that cancer eradication may be achieved by induction of a tumor-specific Th2 inflammatory immune response at the tumor site. Thus, ACT with tumor-specific Th2 cells may represent a highly efficient immunotherapy protocol against cancer.