Nonobese diabetic (NOD) mice are a model for type 1 diabetes in humans. Treatment of NOD mice with end-stage disease by injection of donor splenocytes and complete Freund's adjuvant eliminates autoimmunity and permanently restores normoglycemia. The return of endogenous insulin secretion is accompanied by the reappearance of pancreatic β cells. We now show that live donor male or labeled splenocytes administered to diabetic NOD females contain cells that rapidly differentiate into islet and ductal epithelial cells within the pancreas. Treatment with irradiated splenocytes is also followed by islet regeneration, but at a slower rate. The islets generated in both instances are persistent, functional, and apparent in all NOD hosts with permanent disease reversal.

Insights into the resting and active state structures of TNF superfamily receptors reveal opportunities for drug development.

Previously we have demonstrated that islets of Langerhans treated with donor-specific anti-Ia serum and complement survive when transplanted across the major histocompatibility complex of the mouse. In this study, using immunofluorescence, we demonstrate two morphologically distinct populations of Ia-positive cells scattered within the Ia-negative islet tissue. A large irregularly shaped Ia-positive subset of cells were identified as dendritic cells by using the 33D1 antibody specific for a mouse dendritic cell antigen. The other small, round Ia-positive subset was 33D1 negative. Islets pretreated with anti-dendritic cell antibody and complement prior to transplantation survived in their histoincompatible recipients for greater than 200 days. Rejection of stable islet allografts promptly occurred when transplant recipients were challenged with 1 X 10(5) donor dendritic cells 60 days after transplantation. These results demonstrate an important in vivo role for donor dendritic cells in the stimulation of allograft rejection.

Major barriers to cancer therapy include the lack of selective inhibitors of regulatory T cells (T_regs) and the lack of broadly applicable ways to directly target tumors through frequently expressed surface oncogenes. Tumor necrosis factor receptor 2 (TNFR2) is an attractive target protein because of its restricted abundance to highly immunosuppressive T_regs and oncogenic presence on human tumors. We characterized the effect of TNFR2 inhibition using antagonistic antibodies. In culture-based assays, we found that two TNFR2 antagonists inhibited T_reg proliferation, reduced soluble TNFR2 secretion from normal cells, and enabled T effector cell expansion. The antagonistic activity occurred in the presence of added TNF, a natural TNFR2 agonist. These TNFR2 antibodies killed T_regs isolated from ovarian cancer ascites more potently than it killed T_regs from healthy donor samples, suggesting that these antibodies may have specificity for the tumor microenvironment. The TNFR2 antagonists also killed OVCAR3 ovarian cancer cells, which have abundant surface TNFR2. The antibodies stabilized antiparallel dimers in cell surface TNFR2 that rendered the receptor unable to activate the nuclear factor κB pathway and trigger cell proliferation. Our data suggest that, by targeting tumor cells and immunosuppressive tumor-associated T_regs, antagonistic TNFR2 antibodies may be an effective treatment for cancers positive for TNFR2.

T-regulatory cells (T_regs) are a rare lymphocyte subtype that shows promise for treating infectious disease, allergy, graft-versus-host disease, autoimmunity, and asthma. Clinical applications of T_regs have not been fully realized because standard methods of expansion ex vivo produce heterogeneous progeny consisting of mixed populations of CD4 + T cells. Heterogeneous progeny are risky for human clinical trials and face significant regulatory hurdles. With the goal of producing homogeneous T_regs, we developed a novel expansion protocol targeting tumor necrosis factor receptors (TNFR) on T_regs. In in vitro studies, a TNFR2 agonist was found superior to standard methods in proliferating human T_regs into a phenotypically homogeneous population consisting of 14 cell surface markers. The TNFR2 agonist-expanded T_regs also were functionally superior in suppressing a key T_reg target cell, cytotoxic T-lymphocytes. Targeting the TNFR2 receptor during ex vivo expansion is a new means for producing homogeneous and potent human T_regs for clinical opportunities.