[Frontiers in Bioscience 7, d978-985, April 1, 2002]


Frederick K. Racke 1, Michael Clare-Salzer 2 and S. Brian Wilson 3,4

1 Department of Pathology, Johns Hopkins University, Baltimore, MD 21287, 2 Department of Pathology, College of Medicine, University of Florida, Gainesville, Floridaa 32610, 3 Cancer Immunology & AIDS, Dana Farber Cancer Institute, 44 Binney Street, Boston, MA 02115


Figure 1. A model demonstrating the interaction of CD1d-restricted T cells with myeloid dendritic cells. Activation of invariant Va24JaQ T cells results in the secretion of cytokines and chemokines important for myeloid dendritic cell recruitment and activation. In addition, important cell surface co-stimulatory molecules are also expressed. During myeloid dendritic cell maturation, CD1d is upregulated and activates CD1d-restricted T cells. In addition to the secretion of cytokines and chemokines, activated Va24JaQ T cells upregulate perforin, granzyme B, and Granulysin. The CD1d-dependent secretion of these molecules then results in the lysis of myeloid dendritic cells.

Figure 2. Immunoperoxidase staining of CD1d on paracortical dendritic cells in a reactive lymph node. A monoclonal antibody against CD1d (clone Nor3.2) was used as previously described (11). The upper panels show CD1d expression in paracortical dendritic cells but not in sinus histiocytes. The lower panel shows numerous CD1d positive dendritic cells within the paracortex of a lymph node.

Figure 3. Vaccination with irradiated, GM-CSF secreting B16 melanoma cells is abrogated in CD1d deficient mice. A). Female C57Bl/6 wild type, CD1d deficient or Ja281 deficient mice were immunized subcutaneously on the abdomen with 5x105 irradiated, GM-CSF secreting B16 cells and one week later challenged subcutaneously on the back with 1x106 wild type B16 cells. Animals were considered tumor free if they did not develop tumors during 60 days of observation. The CD1d deficient mice were significantly more susceptible to wild type tumor challenge than controls (c 2, p=2 x 10-6). Vaccination with irradiated, wild type B16 tumor cells failed to elicit protective immunity in either strain (not shown).

Figure 4. a-GalCer prevents diabetes only in wild type NOD mice. Starting at 3-4 weeks of age, Female NOD and NOD/CD1d KO mice were injected with a-GalCer or vehicle on a weekly basis. Diabetes was assessed by monitoring blood glucose levels every week, and mice with two consecutive blood glucose measurement greater than 250 mg/dl were considered diabetic (RR=0.46, p=0.002 a-GalCer NOD wt; RR=1.7, p=0.006 NOD/CD1dKO) NOD/veh N=17, NOD/a-GalCer N=18, NOD/CD1d KO veh, N=15, NOD/CD1dKO a-GalCer N=16.

Figure 5. Treatment with a-GalCer results in the preferential accumulation of myeloid CD8a-/CD11c+ dendritic cells in the lymph nodes draining the pancreas. A. The total number of CD8a+/CD11c+ (lymphoid) and CD8a-/CD11c+ (myeloid) DC in pancreatic and inguinal lymph nodes were determined by FACS 10 days after mice were treated with vehicle, control a-ManCer, or a-GalCer i.p. on days 0 and 4 (n=6/treatment, for a total of 6 experiments). Treatment with a-GalCer resulted in significantly more myeloid DC than lymphoid in the pancreatic lymph node (p=0.005, students t). No CD11c staining was observed on T, B, or NK cells.(data not shown) B & C. Immunohistochemical staining for CD11c+ cells (brown deposits) in representative lymph nodes from mice treated with a-GalCer (B), or vehicle (C).

Figure 6. Acivation of CD1d-restricted NK T cells changes regulates immune responses by changing the balance of dendritic cell subsets. Since human myeloid-derived dendritic cells (DC1) and lymphoid-derived dendritic cells (DC2) regulate CD4+ T helper cell responses, the specific lysis of DC1 cells by NK T cells suggests that their immunomodulatory function is not limited to Th2 bias induced by IL-4 secretion. When co-cultured with T cells, DC1 cells secreted high levels of IL-12 and induced T cells with a Th1 phenotype. Co-culture of T cells with DC2 cells induced a marked Th2 response. Thus, the specific lysis of (DC1) cells by NK T cells may serve as a negative feedback mechanism for limiting Th1 T cell responses. In contrast, the secretion of cytokines that would enhance DC2 differentiation, as predicted for murine myeloid DC, would bias responses toward a Th2 like environment. Although there is strong evidence in the mouse that different dendritic cell subsets reciprocally regulate T cell phenotypes and that NK T cells influence DC function, there is no data available on a direct interaction in between murine NK T cells and DC.