S117Abstracts

Conclusions: Foxp3 expression in human T cells can occurwithout thymic function and does not indicate the presenceof normal thymic activity. The significance of Foxp3expression, likely peripherally-induced, in athymic condi-tions remains unclear.

doi:10.1016/j.clim.2009.03.343

F.86. Deaf1 Isoforms Control Changes in PeripheralTissue Antigen Gene Expression in the Non-obeseDiabetic Mouse Pancreatic Lymph Node duringType I Diabetes PathogenesisLinda Yip1, Rémi Creusot1, Deqiao Sheng1, Pearl Chang1,Margaret Czesak2, Paul Albert2, Ai-ris Collier3, ShannonTurley3, C. Garrison Fathman1, Leon Su1. 1StanfordUniversity, Stanford, CA; 2University of Ottawa, Ottawa,ON, Canada; 3Dana Farber Cancer Institute, Boston, MA

Type 1 diabetes (T1D) is thought to result from a break-down in peripheral tolerance, in part controlled by peripheraltissue antigen (PTA) expression in lymph nodes. In thepancreatic lymph nodes (PLN), a transcriptional regulator,deformed epidermal autoregulatory factor 1 (Deaf1), con-trols the expression of ∼600 genes including various PTAs. Inthe non-obese diabetic (NOD) mouse model of T1D, weidentified a truncated alternatively spliced variant of Deaf1,DF1-VAR1 that hetero-dimerizes with and decreases thetranscriptional activity of Deaf1. The expression of Deaf1correlates with the expression of pancreatic PTAs includinginsulin. Coincident with the onset of destructive insulitis inNOD mice, Deaf1 expression is downregulated in the PLN,while the expression of DF1-VAR1 is upregulated, comparedto its expression in the non-diabetic NOD.B10 mouse. Areduction in Deaf1-controlled PTA expression in the PLN couldlead to decreased peripheral tolerance and help explain thepathogenesis of NOD disease.

doi:10.1016/j.clim.2009.03.344

F.87. Potentially Pathogenic Consequencesof Apoptotic Cell-specific Antibodies inSystemic AutoimmunityPooja Arora1, Joy Das2, Rahul Pal1. 1National Institute ofImmunology, New Delhi, India; 2Memorial Sloan-KetteringCancer Centre, New York, NY

Defects in regulatory mechanisms responsible for self-tolerance can result in inappropriate autoimmune responses.Inefficient clearance of apoptotic debris has been shown tocontribute to the onset of anti-self reactivity. Systemic lupuserythematosus is characterized by the presence of antibodiesto lipids, nucleic acids and proteins. Using B cells sourcedfrom two lupus-prone strains of mice (C57BL/6 lpr/lpr andNZB×NZW (F1)), monoclonal antibodies were developedwhich specifically bound late-stage apoptotic cells in acaspase-dependent manner. Irrespective of isotype or thepresence of somatic mutations, antibodies demonstratedpolyreactive recognition of autoantigens known to be

extruded during apoptosis. While IgM antibodies inhibitedthe phagocytic uptake of apoptotic cells, IgG antibodiesenhanced internalization. An antibody recognizing lysopho-sphatidylcholine prevented the migration of phagocytestowards an apoptotic stimulus. Upon immunization inisogenic animals, antibodies induced anti-antibody andanti-self responses. Elicited antibodies recognized antigensat disparate cellular locations; while immunizing antibodiesbound nuclear antigens, anti-idiotypic antibodies boundmoieties in both the nucleus and the cytoplasm, whilstnevertheless demonstrating a preference for apoptotic cells.Distinct autoantigens were targeted; anti-idiotypic antibo-dies targeted Smproteins, whilst immunizing antibodies wereSmnon-reactive. Hyper-gammaglobulinemia was indicated inimmunized animals, with elevated levels of IgG1, IgG2a andIgG2b observed in serum. The aberrant humoral recognitionof cell death can thus influence the disposal of cellularcorpses and mediate a diversification of auto-reactiveresponses, potentially impacting disease progression.

doi:10.1016/j.clim.2009.03.345

F.89. Elucidating the Antigen Specificity of B CellsPresent within the CNS Lesions of Patients with MSSimon Willis, Stefany Almendinger, Laura Lovato, DavidHafler, Kevin O'Connor. Brigham and Women's Hospital andHarvard Medical School, Boston, MA

The CNS tissue of patients with MS contains focaldemyelinating lesions that harbor an immune cell infiltrate,which often includes B cells. The immunoglobulin (Ig)sequences of these B cells exhibit clear evidence of antigenexperience, yet the antigen(s) driving these B cells remainunknown. To identify these target antigens, single B cellswere isolated directly from MS lesions (using laser capturemicro-dissection), then Ig variable regions were amplifiedand recombinant Ig (rIg) from paired Ig heavy and light chainswere produced from cells representing those that displayedthe features of an antigen-driven response. Twenty rIg wereprepared from five different MS brain specimens and ten rIgfrom control tissues. Recombinant Ig binding candidate MSantigens such asMOG,MBP,αB-crystallin and CNPasewere notrepresented in this sample set. However, a subset of the MS-derived rIg displayed reactivity to lipid components. Work iscurrently underway to assess whether these lipid reactiveantibodies contribute to myelin degradation.

doi:10.1016/j.clim.2009.03.346

F.91. Correlative Analysis of Tissue Transglutaminaseand Deamidated Gliadin IgA and IgG AntibodiesIndicates Minimal T Cell Response AgainstTissue TransglutaminaseShadi Rashtak, Eric Marietta, Joseph Murray. Mayo ClinicCollege of Medicine, Rochester, MN

Background: In celiac disease, a hapten-carrier model hasbeen proposed for the origin of anti-tissue transglutaminase