No abstract

Most tumor-associated Ags are self proteins that fail to elicit a T cell response as a consequence of immune tolerance. Dendritic cells (DCs) generated ex vivo have been used to break tolerance against such self Ags; however, in vitro manipulation of DCs is cumbersome and difficult to control, resulting in vaccines of variable potency. To address this problem we developed a method for loading and activating DCs, in situ, by first directing sufficient numbers of DCs to peripheral tissues using Flt3 ligand and then delivering a tumor-associated Ag and oligonucleotide containing unmethylated CG motifs to these tissues. In this study, we show in three different tumor models that this method can overcome tolerance and induce effective antitumor immunity. Vaccination resulted in the generation of CD8+ T and NK cell effectors that mediated durable tumor responses without attacking normal tissues. These findings demonstrate that unmodified tumor-associated self Ags can be targeted to DCs in vivo to induce potent systemic antitumor immunity.

No abstract

Canine interferon-gamma (CaIFN-gamma) cDNA was expressed in silkworm by infecting recombinant baculovirus. Western blot analyses revealed that the resulting preparation contained various CaIFN-gamma protein molecules. Genetic engineering of CaIFN-gamma to remove potential glycosylation sites resulted in reduced components of the CaIFN-gamma, suggesting that one cause of this heterogeneity was glycosylation. Nonglycosylated CaIFN-gamma produced in silkworm still had several components that were deleted at the carboxy-terminal end. The major component was the CaIFN-gamma protein truncated 17 or 16 carboxy-terminal amino acid residues. CaIFN-gamma showed antiviral activity, class II major histocompatibility complex (MHC) expression-enhancing activity, and antiproliferation activity on tumor cells.

Immortalized human T cell lines were established by cotransfecting c-Ha-ras and c-myc oncogenes to lymph node lymphocytes. The cell lines kept growing for 3 months after establishment without a decrease in growth rate. The cells did not require interleukin-2 (IL-2) for their growth, but addition of IL-2 stimulated the growth of these cells. Flow cytometric analysis revealed that these cells were T cells expressing CD4 or CD8 antigens. A CD4 positive (CD4+) cell line produced IL-6, indicating that the cell line belongs to helper T cells. The CD8 positive (CD8+) cell line possessed cytotoxicity to tumor cells, indicating that the cell line were killer T cells. Both cell lines were able to proliferate in serum-free medium indefinitely.