CD4−8− Dendritic Cells Prime CD4+ T Regulatory 1 Cells to Suppress Antitumor Immunity

Abstract

It is clear that dendritic cells (DCs) are essential for priming of T cell responses against tumors. However, the distinct roles DC subsets play in regulation of T cell responses in vivo are largely undefined. In this study, we investigated the capacity of OVA-presenting CD4−8−, CD4+8−, or CD4−8+ DCs (OVA-pulsed DC (DCOVA)) in stimulation of OVA-specific T cell responses. Our data show that each DC subset stimulated proliferation of allogeneic and autologous OVA-specific CD4+ and CD8+ T cells in vitro, but that the CD4−8− DCs did so only weakly. Both CD4+8− and CD4−8+ DCOVA induced strong tumor-specific CD4+ Th1 responses and fully protective CD8+ CTL-mediated antitumor immunity, whereas CD4−8− DCOVA, which were less mature and secreted substantial TGF-β upon coculture with TCR-transgenic OT II CD4+ T cells, induced the development of IL-10-secreting CD4+ T regulatory 1 (Tr1) cells. Transfer of these Tr1 cells, but not T cells from cocultures of CD4−8− DCOVA and IL-10−/− OT II CD4+ T cells, into CD4−8+ DCOVA-immunized animals abrogated otherwise inevitable development of antitumor immunity. Taken together, CD4−8− DCs stimulate development of IL-10-secreting CD4+ Tr1 cells that mediated immune suppression, whereas both CD4+8− and CD4−8+ DCs effectively primed animals for protective CD8+ CTL-mediated antitumor immunity.

Tumor Apoptotic Bodies Inhibit CTL Responses and Antitumor Immunity via Membrane-Bound Transforming Growth Factor-β1 Inducing CD8+ T-Cell Anergy and CD4+ Tr1 Cell Responses

“…A previously described procedure was used for generation of mature DCs expressing CD11c, Ia b , CD40, CD54, and CD80 (data not shown) from mouse splenocytes in culture medium containing GM-CSF (20 ng/mL) and IL-4 (20 ng/mL; ref. 23). These splenic DC cultured in the above medium containing OVA (0.5 mg/mL) and in the above medium with irradiated (9,000 rad) P815 tumor cells at a ratio of 1:2 for overnight (22) were termed DC OVA and DC P815 , respectively.…”

“…EG7 is an ovalbumin (OVA) gene-transfected tumor cell line obtained from American Type Culture Collection and was maintained in DMEM (Life Technologies), 10% FCS, and G418 (0.5 mg/mL; Life Technologies). LB27, a B-cell hybridoma cell line expressing Ia b , was also obtained from ATCC (23). The FITC-conjugated monoclonal rat anti-mouse MHC I antibody and the polyclonal rabbit anti-OVA antibody were purchased from Pharmingen.…”

Anatomic location defines antigen presentation by dendritic cells to T cells in response to intravenous soluble antigens

“…Although CD8a -CD11b + DC, CD8a + CD11b -DC and B220 + plasmacytoid DC (PDC) are present in every secondary lymphoid tissue, there is an additional double-negative population (CD8a -CD11b -) in LN that is not dominant in spleen and a double-positive subset (CD8a + CD11b + ) that represents a major population only in LN other than mesenteric LN (MLN) [5,6]. A number of experimental models, most performed with splenic DC, suggest that each subset serves a unique role in the immune system [2,[6][7][8][9][10][11][12][13][14][15][16]. Moreover, CD8a + and CD8a -splenic DC have different gene-expression profiles, a finding that strongly supports a functional difference between these two subsets [17].…”

Novel Exosome-Targeted CD4+ T Cell Vaccine Counteracting CD4+25+ Regulatory T Cell-Mediated Immune Suppression and Stimulating Efficient Central Memory CD8+ CTL Responses

“…DCs were generated as described previously (17). Briefly, spleen cells were prepared in PBS with 5 mM EDTA, washed, and incubated in culture medium with 7% FCS at 37°C for 2 h. Nonadherent cells were removed by gentle pipetting with warm serum-free medium.…”