Eradication of established tumors by CD8+ T cell adoptive immunotherapy.

We generated the DUC18 T cell receptor transgenic mouse expressing an H-2Kd -restricted transgenic T cell receptor specific for the syngeneic CMS5 fibrosarcoma rejection antigen mutated ERK2(136-144). DUC18 mice were capable of specifically eliminating lethal CMS5 tumor challenges, and transfer of DUC18 splenocytes to naive nontransgenic recipients conferred protection from subsequent and established CMS5 tumor burdens. Eradication of established tumor burdens by adoptive transfer of DUC18 splenocytes was dose and time dependent. Transferred tumor-specific T cells remained functional in vivo and capable of rejecting small tumors even in the presence of large, established tumor burdens. These findings highlight the kinetic battle between tumor growth and the production of a tumor-specific response and have critical implications for effective adoptive immunotherapy.

Class I-restricted cytotoxic T cell recognition of split peptide ligands.

We developed a novel approach to probe the molecular basis of TCR recognition of the MHC class I-peptide complex and to determine how constraints placed on peptide binding by the class I molecule influence T cell recognition. We synthesized peptide pairs derived from the N- and C-terminal regions of class I peptide ligands in which the TCR contacts and dominant binding residues were placed together or were separated. Complementary peptide pairs derived from two well-characterized Ld peptide ligands, tum- (QNHRALDL) and p2Ca (LSPFPFDL), were tested for the ability to sensitize targets for recognition by peptide-specific cytotoxic T lymphocytes (CTL). The tum-derived tetramer QNHR, containing both primary TCR contact residues (H17 and R18), is recognized only when used in combination with ALDL which contains the primary binding residues (A19, D21 and L22). This suggests that both peptides of the pair contribute to positioning of the TCR contacts. Remarkably, CTL clone P24 recognized target cells sensitized with a trimer (QNH) combined with a pentamer (RALDL), demonstrating that TCR recognition can occur when the TCR contacts are separated (placed on separate peptide subunits). For the p2Ca peptide LSPFPFDL, the C-terminal tetramer PFDL, which contains both the primary TCR contact residue (P) and the dominant binding residue (L), is sufficient for recognition. In addition, PFDL was able to bind effectively to Ld and to activate naive antigen-specific T cells. These data suggest that peptide subunits and complementary peptide pairs composed of trimeric, tetrameric or pentameric peptides can bind independently to the Ld molecule in the same register and orientation as they do when contained within the parent peptide.

Beta cell apoptosis in T cell-mediated autoimmune diabetes.

Insulin-dependent diabetes mellitus results from T cell-mediated destruction of insulin-producing, pancreatic islet beta cells. How this destruction takes place has remained elusive--largely due to the slow kinetics of disease progression. By crossing a transgenic mouse carrying a beta cell-specific T cell receptor onto the NOD.scid background, we produced a simplified but robust and accelerated model of diabetes. This mouse produces CD4+ T cells bearing transgenic T cell receptor but is devoid of CD8+ T cells and B cells. More importantly, this mouse develops a rapid diabetes, which has allowed us to record and quantify beta cell death. We have determined that beta cells within the inflamed islets die by apoptosis.