Baylor Institute for Immunology Research (BIIR): Abstracts and Video Presentations from the Third Annual Baylor Symposium and Workshop on Human Immunology and Biodefense, November 4-5, 2006

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Third Annual Baylor Symposium and Workshop on Human Immunology and Biodefense, November 4-5, 2006

Videos from the Symposium are available for you to watch online.

	Module 1: Welcome Virginia Pascual, MD - Investigator, Baylor Institute for Immunology Research, Dallas, Texas, Michael Ramsay, MD, FRCA - President, Baylor Research Institute, Dallas, Texas Jacques Banchereau, PhD - Director, Baylor Institute for Immunology Research, Dallas, Texas Video in WMX format: 16:10 minutes, 37.59 MB
	Module 2: Vaccine Session I Manipulation of Dendritic Cells for Generation of Novel Human Vaccines Jacques Banchereau, PhD Director Baylor Institute for Immunology Research Abstract Video in WMX format: 43:20 minutes, 84.05 MB
	Module 3: Vaccine Session I Development of New Vaccines with TLR-Based Adjuvants Robert Coffman, PhD Vice President & Chief Science Officer Dynavax Technologies Berkeley, CA Video in WMX format: 50:10 minutes, 60.15 MB
	Module 4: Vaccine Session I Use of the Salmonella Type III Secretion System for Vaccine Development Jorge Galan, PhD Professor & Chairman Section of Microbial Pathogenesis Yale University School of Medicine New Haven, CT Video in WMX format: 51:52 minutes, 109.13 MB
	Module 5: Vaccine Session I Challenges in the Development of an HIV Vaccine Barney Graham, MD, PhD Chief, Viral Pathogenesis & Clinical Trials Core National Institutes of Health Bethesda, MD Video in WMX format: 43:36 minutes, 55.69 MB
	Module 6: B Cell Session Germinal Center, B Cell Gymnastics Michel Nussenzweig, MD, PhD Investigator The Rockefeller University New York, NY Abstract Video in WMX format: 39:52 minutes, 88.07 MB
	Module 7: B Cell Session TBA: T, B, & Accessory Cells Antonio Lanzavecchia, MD Director Institute for Research in Biomedicine Bellinzona, Switzerland Abstract Video in WMX format: 50:58 minutes, 63.71 MB
	Module 8: B Cell Session Convergent Evolution of Two Adaptive Immune Systems Max Cooper, MD Professor, University of Alabama at Birmingham School of Medicine Birmingham, AL Abstract Video in WMX format: 1 hour 3 minutes, 112.92 MB
	Module 9: Vaccine Session II Understanding Induction of Mouse T_CD8+ Responses to Viruses to Enable Rational Design of Vaccines for Eliciting Cellular Immunity Jonathan Yewdell, MD, PhD Cellular Biology Section Chief National Institute of Allergy & Infectious Diseases Bethesda, MD Abstract Video in WMX format: 47:29 minutes, 75.36 MB
	Module 10: Vaccine Session II What Makes Dendritic Cells So Special Ira Mellman, PhD Chair, Department of Cell Biology Yale University School of Medicine New Haven, CT Abstract Video in WMX format: 55:11 minutes, 70.55 MB

Abstracts from the Symposium

Novel IFN regulated and non IFN regulated gene signatures in monocytes from Systemic Lupus Erythematosus (SLE) patients
Pinakeen Patel^{1, 2}, Damien Chaussabel¹, Edsel Arce³, Victoria Cantrell¹, Jacques Banchereau¹ and Virginia Pascual¹. ¹ Baylor Institute for Immunology Research, Dallas, TX 75204; ² Baylor University, Waco, TX 76798; ³ Children's Hospital Central California, Madera CA 93638.

Monocytes from SLE patients function as Dendritic cells (DCs), as they activate CD4 T cells in vitro. Furthermore, SLE serum induces healthy monocyte differentiation into DCs. This activity is due to the presence of type-I IFN in SLE serum, as blocking this cytokine abrogates this effect. Other factors present in SLE serum are necessary however, as addition of type I IFN to fetal calf serum does not reproduce the DC differentiating capacity of SLE serum. To understand the effect of IFN and other serum-derived factors on SLE monocyte activation, we analyzed the gene expression profiles of monocytes from untreated SLE patients and compared them with those of healthy controls before and after in vitro exposure to i) SLE serum, ii) SLE serum in the presence of type-I IFN blockers, and iii) recombinant IFNa2b. These profiles were also compared with those of blood mDCs from healthy donors and blood monocytes from SLE patients on immunosuppressive medications. Results and conclusions: 1) SLE monocytes differentially express both IFN-regulated and non IFN-regulated genes; 2) one third of these genes are also differentially expressed in blood mDC; 3) medication has a profound effect on the gene expression profile of SLE monocytes. These studies may shed light on the pathogenic factors driving the activation of myeloid DCs in SLE patients.

Follicular Helper T cells: Development and Function
Rimpei Morita¹, Eynav Klechevsky¹, Francine Briere², Casey Glaser¹, Giny Cao¹, Karolina A. Palucka¹, Jacques Banchereau¹, and Hideki Ueno¹. Baylor Institute for Immunology Research, Dallas, TX, 752041, Schering-Plough Laboratory, Dardilly, France².

T cell help provided to B cells is fundamental for the production of high-affinity memory B cells and long-lived plasma cells. A subset of CD4⁺ T cells which expresses the chemokine receptor CXCR5 has been identified as a specialized T cell population for B cell help in the germinal center (GC) in secondary lymphoid organs. This CD4+ T cell subset, follicular helper T cells (TFH), is instrumental for GC generation, and induces B cell proliferation, somatic-hypermutation, and class-switch recombination. We found that memory CD4⁺ T cells expressing CXCR5 in the blood (blood TFH) have an exclusive function to prime naïve B cells to differentiate into immunoglobulin-producing plasma cells. Only blood TFH cells, but not CXCR5-CD4⁺ memory T cells or naïve CD4⁺ T cells, were able to induce the proliferation as well as immunoglobulin production by priming naïve B cells upon cognate interaction. This B cell help function was totally dependent on IL-21 secreted by TFH cells, and the addition of external IL-21 to the culture with non-TFH memory T cells partially restored immunoglobulin production from naïve B cells. Furthermore, BAFF/APRIL produced by TFH cells was essential for the B cell priming/differentiation. These findings support the concept that TFH is a CD4⁺ T cell entity distinct from any other CD4⁺ T cell subset. As the mechanism of the development of TFH cells is largely unknown, we investigated subsets of dendritic cells (DCs) for their capacity to induce TFH cells. Human myeloid DC consists of two major subsets: Langerhans cells (LCs) and interstitial DCs (IntDCs), both of which have unique functions to skew T cell differentiation. Strikingly, only IntDCs, both in vitro generated and ex vivo isolated, were able to induce TFH development from naïve CD4⁺ T cells, whereas LCs lacked this capacity. IntDCs, which migrate to just beneath the B cell follicles of the outer paracortex of secondary lymphoid organs, have a unique ability to prime naïve B cells into IgM-secreting plasma cells, and thus have a fundamental role in controlling humoral immunity.

Circulating tumor-associated antigen specific regulatory CD4⁺ T cells in patients with metastatic melanoma
Luis Vence, Karolina A. Palucka, John E. Connolly, Joseph W. Fay, Jacques Banchereau, and Hideki Ueno,. Baylor Institute for Immunology Research, Dallas, TX, 75204.

An emerging concept in cancer is the deleterious role that regulatory T cells (Tregs) play in tumor development and progress. In this study, we show that blood from metastatic melanoma patients carries Tregs specific for multiple epitopes of several known melanoma antigens. We used an assay referred to as EPIMAX, where the main component is measurement of multiple cytokines in the culture of blood mononuclear cells stimulated with overlapping peptides encoding antigens. This simple method allows simultaneous identification of: i) the epitope of CD4⁺ and CD8⁺ T cells; ii) the cytokine secretion pattern of the antigen-specific T cells; and iii) the proliferative capacity of the specific T cells. Multiple peptides derived from NY-ESO1, Survivin, TRP-1, and gp100 were identified to induce IL-10 secretion in the melanoma patient's PBMC cultures. These peptides were found to represent the epitopes for Tregs that produce large amounts of IL-10. Each identified peptide was unique to a given patient, and did not induce IL-10 secretion in other patient's PBMC cultures. Stimulation of PBMCs with IL-10-secreting peptides induced the proliferation of a small fraction of CD4⁺ T cells. After expansion, these peptide-responding cells were indeed specific for the peptide used in the initial culture, and produced large amounts of IL-10 and a minimal amount of IL-2 in response to the specific peptide. These Tregs expressed high amounts of FoxP3 and CTLA4, and suppressed the proliferation and cytokine secretion of autologous effector T cells. Similar to CD4⁺CD25⁺ thymus-derived Tregs, the suppression required cell-to-cell contact. The complete absence of similar tumor antigen-specific Tregs in healthy individuals suggests their induction and/or expansion in an environment conditioned by cancer.

Role of splenic B cells in the induction of peripheral tolerance elicited through the anterior chamber of the eye
Hossam M. Ashour^* and Jerry Y. Niederkorn^**,
^* Immunology Graduate Program, **Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, TX 75390

Antigens introduced into the anterior chamber (AC) of the eye induce a form of peripheral immune tolerance termed AC-associated immune deviation (ACAID). ACAID mitigates ocular autoimmune diseases and promotes corneal allograft survival. Ags injected into the AC are processed by F4/80+ APCs, which migrate to the thymus and spleen. In the spleen, ocular APCs induce the development of Ag-specific B cells that act as ancillary APCs and are required for ACAID induction. In this study, we show that ocular-like APCs elicit the generation of Ag-specific splenic B cells that induce ACAID. However, direct cell contact between ocular-like APCs and splenic B cells is not necessary for the induction of ACAID B cells. Peripheral tolerance produced by ACAID requires the participation of ACAID B cells, which induce the generation of both CD4+ regulatory T cells (Tregs) and CD8+ Tregs. Using in vitro and in vivo models of ACAID, we demonstrate that ACAID B cells must express both MHC class I and II molecules for the generation of Tregs. These results suggest that peripheral tolerance induced through the eye requires Ag-presenting B cells that simultaneously present Ags on both MHC class I and II molecules.

Humice to test efficacy of vaccines against influenza virus
Chun I, Yu; Florentina Marches; Alexander Pedroza,; Mike Gallegos; Adolfo Garcia-Sastre*; Jacques Banchereau; and A. Karolina Palucka.
Baylor NIAID Cooperative Center for Translational Research on Human Immunology and Biodefense, Baylor Institute for Immunology Research, Dallas, Texas and * Mount Sinai School of Medicine, New York

The paucity of in vivo models of human disease represents a major drawback in translational research. Murine models are essential for the demonstration of genetic links. However, the results obtained in mice cannot always be directly extrapolated to humans because of differences between the species. When NOD-SCID beta2m^-/- mice are engrafted with human CD34+ hematopoietic progenitors, they develop all subsets of human dendritic cells and B cells. T cells can be reconstituted by adoptive transfer. Upon intranasal inoculation with H1 influenza viruses, viral replication in the lung can be detected, Humice become sick, loose weight and eventually die. Infected Humice can develop influenza-specific immunity as demonstrated by serum titer of specific IgM and IgG. Humice can also develop influenza-specific immunity upon vaccination with ex vivo generated dendritic cells (DCs). Single vaccination with heat-inactivated influenza virus or Flu-MP peptide loaded DCs leads to expansion of Flu-MP tetramer binding CD8+ cells that can secrete IFN gamma. The T cells can be detected in draining lymph nodes but also in the blood and in the lung demonstrating unaltered migration of effector T cells in Humice. Vaccination with DCs loaded with heat-inactivated influenza virus leads to development of influenza-specific immunoglobulins in the serum including IgG demonstrating that isotype switch could occur. Isotype switch is associated with somatic mutation. Importantly, Influenza-specific Igs are protective and can inhibit influenza-virus induced hemagglutination. Thus, this model will permit testing novel vaccines against influenza virus, including H5, most particularly vaccines based on in vivo targeting of human DCs.

Dead cell-associated poly I:C inhibits cross-presentation by human dendritic cells
Davor Frleta, Jacques Banchereau, and A. Karolina Palucka.
Baylor NIAID Cooperative Center for Translational Research on Human Immunology and Biodefense, Baylor Institute for Immunology Research, Dallas, Texas

Targeting adjuvant with tumor antigen to dendritic cells (DCs) could improve vaccine immunogenicity and outcomes of cancer immunotherapy. In murine models, DCs loaded with dead cells full of poly I:C, a Toll-like receptor (TLR) 3 agonist, show improved cross-priming of antigen-specific CD8⁺ cytotoxic T lymphocytes (CTLs). We found that loading human DCs with dead melanoma cells containing poly I:C (poly I:C-bodies) results in the inhibition of cross-priming of CTLs in vitro. Thus, CD8⁺ T cells cultured with DCs loaded with poly I:C bodies i) expand poorly; and 2) do not kill melanoma cells used to load the DCs, suggesting inhibition of effector cell differentiation. CD8⁺ T cell expansion and differentiation is not inhibited when DCs are loaded with tumor bodies and soluble poly I:C delivered in trans. These results suggest that inhibition observed with cell-associated poly I:C is due to localization of poly I:C within the tumor cells. DCs loaded with poly I:C-bodies and pulsed with Flu peptide elicit strong recall response and expansion of Flu tetramer-specific CD8⁺ T cells. Furthermore, DCs loaded with poly I:C-bodies induce strong proliferation of allogeneic CD8⁺ T cells. These results demonstrate that the overall antigen presenting capacity of DCs is not altered. Therefore, a possible explanation is specific alteration in MHC class I antigen processing and/or loading.

Thus, we conclude that poly I:C-bodies specifically inhibit cross-presentation by DCs. These results have relevance for tumor vaccines utilizing human DCs. There are also implications for DC biology during viral infection. Viral infection is associated with dying cells, many which contain viral stimuli, such as double-stranded RNA (dsRNA), a TLR3 agonist. Our results suggest that dsRNA within dying cells could impair DC-mediated cross-presentation, possibly to prevent activation of CTLs specific for cell-associated antigens.