#3403- ToleranceSunday, June 43:30—5:30 pm

OR.97. Respiratory Syncytial Virus Subverts theImmune Response Through the Induction ofTolerogenic Myeloid Dendritic Cells.John Connolly, Michelle Gill, Yaming Xue, Vikram Bhuta,Jennifer Shay, Jacques Banchereau. Immunology, BaylorInstitute for Immunology Research, Dallas, TX.

Respiratory Syncytial Virus (RSV) infection is the primarycause of hospitalization in the first year of life. Here weshow that RSV exposure of human peripheral blood mDCsinduces their conversion to tolerogenic dendritic cells. RSVexposed DCs display a unique cytokine and chemokinepattern and a surface receptor profile consistent with atolerogenic phenotype, including the selective upregulationof ITIM containing receptors ILT3, ILT4, ILT5, SIGLEC,SLAMF1, LAIR1 and LAIR2 as well as ligands for ITIMcontaining receptors such as PDL-1 and HLA-G . MHC class-II surface translocation is blocked by viral exposure, whilecostimulatiory molecule expression is upregulated. Func-tionally, RSV exposed dendritic cells are unable to promoteCD4+ T-cell proliferation in an allogeneic setting. FurtherRSV exposed mDCs can inhibit allogenic proliferation fromunexposed DCs in trans, in a manner dependent on cellcontact. While there are numerous examples of pharmaco-logic and cytokine mediated upregulation of DC inhibitoryreceptors, these data demonstrate that RSV selectivelyperturbs dendritic cell maturation toward a tolerogenicphenotype and function suggesting a novel mechanism forviral immune evasion.

doi:10.1016/j.clim.2006.04.402

OR.98. Abrogation of Anti-Retinal Autoimmunity inIL-10 Transgenic Mice Due to Inhibition of Primingand Effector Function of Auto-Reactive T-Cells.Rajeev Agarwal,1 Angelia Viley,1 Phyllis Silver,1 RafaelGrajewski,1 Mitchell Kronenberg,2 Peter Murray,3 RobertRutschman,3 Chi-Chao Chan,1 Rachel Caspi.1 1Laboratory ofImmunology, NEI, NIH, Bethesda, MD; 2Division ofDevelopmental Immunology, La Jolla Institute for Allergyand Immunology, San Diego, CA; 3Department of InfectiousDiseases, St. Jude Children Hospital, Memphis, TN.

We previously have shown that IL-10 inhibits experimentalautoimmune uveitis (EAU). Here we examine the effect oftargeted overexpression of IL-10 on EAU. We used 3 lines oftransgenic (Tg)mice: two expressing IL-10 in activated T-cells(inducible) under the IL-2 or PA promoters (IL-2/IL-10 or PA/IL-10, respectively) and one expressing IL-10 in macrophages(constitutive) under the CD68 promoter (CD68/IL-10). IL-10Tg and non-Tg mice were immunized with a uveitogenicregimen of the retinal antigen IRBP. Compared to wild type,macrophage-expressed IL-10 completely abrogated diseaseand reduced Ag-specific immunological responses. In con-trast, expression of IL-10 in activated T-cells only partially

protected from EAU and Ag-specific responses were onlymarginally reduced. Ag-specific cytokine profile in all 3 IL-10Tg genotypes revealed a global suppression of pro- and anti-inflammatory cytokines (except IL-10). We hypothesized thatthe endogenous overexpression of IL-10 may impede thepriming and/or function of effector T-cells. To address this, aproliferation assay was performed using purified T-cells fromnaive OVATCR-Tg mice, cultured with OVA peptide presentedby APC from the different IL-10 Tg or WT genotypes.Compared to WT controls, Ag-specific proliferation wasreduced in CD68/IL-10 Tg mice, and to a lesser extent in IL-2/IL-10 and PA/IL-10 Tg mice, suggesting reduced T-cellpriming. To examine the efferent phase of the disease, weadoptively transferred cells from IRBP-immunized WT donorsinto IL-10 Tg mice. In contrast to WT recipients, CD68/IL-10Tg mice were completely protected from EAU. We concludethat (i) constitutive expression of IL-10 in macrophages ismore protective in this model than its inducible expression inT-cells (ii) the inhibition affects priming as well as function ofuveitogenic effector T-cells.

doi:10.1016/j.clim.2006.04.403

OR.99. IL-10 and Tregs in Rhesus Macaques (Rm)with Resolute, Drug-Free, Pancreas Islet Allograft(PITx) Tolerance for NNNN6 Years.Judith Thomas,1 Karen Goodwin,1 Celina Rodriguez,1

Gansuvd Balgansuren,1 Clement Asiedu,1 PatricioAndrades,1 David Neville.2 1Surgery, University of Alabamaat Birmingham, Birmingham, AL; 2Biophysical ChemistrySection, National Institute of Mental Health, NIH, Bethesda,MD.

PITx is emerging as a clinical treatment for Type 1 Diabetes(TID). A key hurdle is to achieve stable tolerance to bypasschronic immunosuppressive drugs. We developed, in RM, aunique and effective approach to PITx tolerance, utilizingbrief anti-CD3 immunotoxin and 15-deoxyspergualin therapy.Here, we document the metabolic profile and immunologicaladaptations in tolerant euglycemic RM, free of insulin orimmunosuppressive therapy for N6 yr post-transplant. TIDwas induced by STZ (140 m/kg) in 7 juvenile RM followed by asingle intraportal infusion of donor islets 2-4 wk later. Here,we update the non-fasting (NF) BG profile, IVGTT, resting C-peptide, and stimulated systemic and transhepatic release ofinsulin and c-peptide as well as serum IL-10 and bloodCD4+CD25+ Treg levels in 3/7 long term surviving (LTS)recipients now N6 yr post-transplant. Among LTS, NF BG hasremained stable (50-150 mg/dl) as have IVGTT Kg values.LTS 1st phase peak insulin (26-37AU/ml) is below normal(52AU/ml), while 2nd phase insulin exceeds normal. HbgA1Cand resting C-peptide remain normal. Stimulated C-peptideresponses show C-peptide production is from the liver(allograft site), not the native pancreas. Thus euglycemia ismaintained by the transplant. IL-10 levels in LTS peaked at1200 pg/ml vs. normal (b30 pg/ml) and have remainedelevated (100-700pg/ml). In contrast, recipients failing toestablish stable PITx tolerance did not generate or sustainserum IL-10 elevation. The frequency of CD4+CD25+ cells inLTS was also elevated (9-14% of CD4+ cells vs. 1-4% in

Abstracts S41