This study was supported by Nature Science Foundation of Shandong Province (Grant Number: ZR2010HL038). Science and Technology Development Projects of Jining City (Grant Number: 2012jnjc16). None. “
“Lymphodeleption prior to adoptive transfer of tumor-specific T cells greatly improves the clinical efficacy of adoptive T-cell therapy for patients with advanced melanoma, and increases the therapeutic efficacy of cancer vaccines in animal models. Lymphodepletion reduces competition between lymphocytes, and thus creates buy Talazoparib “space” for enhanced expansion and survival of tumor-specific T cells. Within the lymphodepleted host, Ag-specific T cells still need to compete

with other lymphocytes that undergo lymphopenia-driven proliferation. Herein, we describe the relative capacity of naïve T cells, Treg, and NK cells to undergo lymphopenia-driven proliferation. We found that the major population that underwent lymphopenia-driven proliferation was the CD122+ memory-like T-cell population (CD122+CD8+ Treg), and these RGFP966 cells competed with Ag-driven proliferation of melanoma-specific T cells. Removal of CD122+CD8+ Treg resulted in a greater expansion of tumor-specific T cells and tumor infiltration of functional effector/memory T cells. Our results demonstrate the lymphopenia-driven proliferation of CD122+CD8+ Treg in reconstituted lymphodepleted

mice limited the antitumor efficacy of DC vaccination in conjunction with adoptive transfer of tumor-specific T cells. Due in large part to the limited expansion and survival of vaccine-induced tumor Ag-specific T cells, active specific immunotherapy of tumor-bearing hosts with tumor vaccines has generally been ineffective

1. Therefore, a major goal of current T-cell based immunotherapy protocols is to induce a large number of tumor-specific T cells capable of mediating regression of established tumors and maintaining long-term memory to prevent tumor recurrence. Lymphodepletion has been recently demonstrated to facilitate the expansion and survival of therapeutic, adoptively Thymidylate synthase transferred in vitro-expanded T cells, which induced tumor regression in patients with melanoma (see review in 2). Concurrently, we and others have demonstrated that vaccination induced a dramatic expansion of tumor-specific T cells, and improved the efficacy of active immunotherapy in reconstituted lymphodepleted mice 3–7. While lymphopenic conditioning has been shown to benefit antitumor immunity, and aids in the establishment of the T-cell repertoire in neonatal mice 8, it was detrimental for transplant tolerance 9, and precipitated the development of autoimmune disease 10. Homeostatic proliferation, or more precisely, lymphopenia-driven proliferation of lymphocytes in irradiated or lymphocyte-deficient mice, is a well-studied phenomenon (see review 11).