Chairman

Dr. Irving L. Weissman (1989-1994, Member 1985-1988) Professor Department of Pathology Stanford University School of Medicine 300 Pasteur Drive Palo Alto, California 94305-5324

Chairman

Dr. Tadamitsu Kishimoto (1986- , Member 1981-1986) Professor Faculty of Medicine Osaka University 2-2 Yamadaoka, Suita Osaka 565, Japan

Dr. Laurie H. Glimcher (1993-1996)
Professor of Immunology and Medicine
Department of Cancer Biology and Medicine
Harvard School of Public Health
665 Huntington Avenue
Building 1, Room 705
Boston, Massachusetts 02115

*Dr. Leroy E. Hood (1991-   , 1987-1994)
William Gates III Professor
Department of Molecular Biotechnology, GJ-10
University of Washington School of Medicine
4909 25th Avenue, N.E.
Seattle, Washington 98195-0001

Dr. Ellen Vitetta (1994-1997)
Professor of Microbiology
University of Texas Southwestern Medical School
5323 Harry Hines Boulevard, NB9-210
Dallas, Texas 75235-8576

*incoming Board chair

Dr. Hideo Nariuchi (1990-   )
Professor
The Institute of Medical Science
University of Tokyo
4-6-1 Shirokanedai, Minato-ku
Tokyo 108, Japan

Dr. Ko Okumura (1994-   )
Professor
Faculty of Medicine
Juntendo University
2-1-1 Hongo, Bunkyo-ku
Tokyo 113, Japan

Dr. Takehiko Sasazuki (1986-   )
Professor
Medical Institute of Bioregulation
Kyushu University
3-1-1 Maidashi, Higashi-ku
Fukuoka 812, Japan

Immunology Boards USJCMSP

The long-term objectives of the Immunology Boards are to elucidate the cellular and molecular mechanisms of the immune response and the pathogenesis of immunologic disorders and to pursue the areas of immunology that are needed to expedite vaccine development to prevent infectious diseases and new methods to treat and prevent immunologic diseases. The Boards are "unique" because basic immunology is essential to understanding the pathogenesis of immunologic and infectious diseases.

Guidelines

1. Molecular studies on the genetic organization of the lymphoid system including gene targeting and transgenes, and applications including gene knock-out and other strategies in transgenic mice to study immunity and disease model
2. Cellular and molecular studies of lymphocyte activation, proliferation, and differentiation with special reference to cytokines and their signalling mechanisms
3. Cellular, molecular, and immunogenetic approaches to T cell recognition and their repertoire selection
4. Cellular and molecular studies of the regulation of the immune response with special emphasis on pathogenesis for human autoimmune disease
5. Studies on the development of new and more effective methods for the diagnosis, treatment, and prevention of immune and infectious diseases including vaccine development
6. Mechanisms to support the interaction of immunologists and the exchange of information and material between the two countries.

Broad Goals

In 1981, the Joint Committee of the USJCMSP formed the Immunology Boards to elucidate the cellular and molecular mechanisms associated with the immune response and the pathogenesis of immunological disorders, to advance immunological research to expedite the development of vaccines to prevent infectious diseases and to examine the use of new methods to treat and prevent immunologic diseases.

During the past 5 years, Board members have carried out important studies in areas of immunologic research directly related to these goals. This includes research on the immunobiology of human and mouse hematopoietic stem cells; mechanisms that control the rearrangement of elements that compose the variable segments of immunoglobulin genes and the T-cell receptor; cellular and molecular roles of class II major histocompatibility antigens in autoimmune disease; molecular and cellular events in normal immune responses and the aberrations that result in diseases, especially autoimmune diseases; monoclonal antibodies and conjugated monoclonal antibodies as anti-tumor agents; molecular regulation of B-cell development; role and function of superantigens in disease states; and mechanisms and significance of antigen processing and presentation.

Progress/Accomplishments

During the past 5 years, the outstanding progress in immunology generated during the decade of the 80's has continued to accelerate and expand. This progress has been most gratifying as it has led us ever closer to the goal of applying basic knowledge directly to the diagnosis, treatment, and prevention of infectious and immunologic diseases. Building on significant research advances and new technology development that have allowed us to determine gene structure and to grow immune cells in vitro, researchers have applied powerful new molecular and genetic techniques to the development of new strains of transgenic animals and to the ablation of specific genes (gene knockouts) to advance our understanding of immune function. The promise of previous years has been fulfilled by the acquisition of a wealth of critical information on the proliferation of cytokines that interact with each other in a complex way to promote the differentiation and activation of immune cells, the sequencing and fine detail of molecules, central to delineating immune structure and regulation, and the linkage between antigen processing and recognition, molecular control, and the role of the HLA complex in the disease processes, particularly autoimmune disease. Moreover, the past 5 years have seen major advances in elucidating the complex molecular cascades that comprise the molecular signalling through which immune cells communicate, an improved understanding of an old problem, namely, immune tolerance and the role of defective signalling in anergy, and an understanding of the role of oncogenes in apoptosis.

Members of the Immunology Boards have been at the forefront of many of these exciting new advances.

Studies on Hematopoietic Stem Cells (HSC)

A number of in vitro and in vivo assays and advanced cell sorter techniques have been used to demonstrate that isolated HSC in mice represent a very rare subset (less than 1/2000) of the hematopoietic cells in fetal liver and adult bone marrow cells. These HSC have been isolated to study mechanisms of self-renewal and differentiation, to define their response and differentia-tion patterns to growth factors, and to examine their role in bone-marrow transplantation across genetic/immunologic barriers. Using the SCID-hu mouse model, human HSC have been isolated and found to have a frequency in human fetal bone marrow similar to that of mouse HSC. Moreover, these HSC comprise a very heterogeneous population. Resting HSC are best able to self-renew, lack all blood cell lineage markers on their surface, and give rise to sustained reconstitution. HSC that give rise to short-term multilineage repopulation are characterized by a specific set of differentiation markers. The addition of two cytokines, CSF (colony stimulating factor) and GM-CSF (granulocyte monocyte-colony stimulating factor), results in the mobilization of HSC from bone-marrow to the blood. In thymic development, fetal HSC gives rise to both fetal and adult outcomes, whereas adult HSC only gives rise to adult outcomes when both are tested in fetal thymic microenvironments.

Rearrangement and Recombination in Immunoglobulin and T-Cell Receptor Variable (V) Region Genes

A fuller understanding of the mechanisms that control the rearrangement and common recombination system of V-region genes is now available through the construction, by various genetic approaches, of seven independent mutations that affect various steps in the process. These are mutations of RAG-1 or RAG-2 genes that result in the inability to initiate the VDJ recombination reaction, murine scid and the CHO cell V-3 mutation that allow initiation of the reaction and RS-join formation but block coding-joins formation, two additional CHO cell mutations (xrs-6 and XR-1) that allow initiation of the reaction, but block both the RS and the coding-joins formation, and a TdT loss mutation in novel RAG-2 deficient blastocyst complementation system that does not eliminate the VDJ recombination reaction but does eliminate addition of extra nucle-otide. RAG-2 deficient mice are viable but show a severe combined immune deficiency due to a total inability to initiate VDJ recombination and thereby generate mature lymphocytes.

The CHO line xrs-6, defective for double strand break repair, is also defective in the free double-stranded DNA end binding activity associated with the Ku protein complex, the DNA binding component of DNA-dependent protein kinase. Expression of the human Ku 80 protein corrects all three defects in xrs-6 cells, indicating that Ku is involved in DNA repair and VDJ recombi-nation, perhaps through a mechanism that involves its end-binding activity. Mutant B cells, in which the IgH 3' enhancer (3'EH) and several kb of the 3' and 5' flanking sequence were replaced, undergo normal VDJ recombination and secrete IgM but do not secrete IgG2a, IgG2b, IgG3, or IgE. The 3'EH mutation, either by deleting a critical element or by inserting a competing promoter, is thought to disrupt the function of a regulatory element that influences class switching to at least four different CH genes that are located a substantial distance (as far as 120kb) upstream of the mutation.

Studies on the Role of Tran-scription Factor on B-Cell Development

The DNA-binding protein, NF-kB, is a superb model of how transcription factors can regulate the development of B cells. NF-kB, following its own activation from an inactive form in the cytoplasm where it is bound to an inhibitor, IkB, enters the nucleus, binds to the k enhancer, and activates k gene transcription. This process is controlled by a complex set of events. The inhibitor interacts with the factor through its two Rel-related subunits, p50 and p65. Adequate levels of the inhibitor are maintained by upregulation by the k65 subunit. Thus, multiple regulatory events are responsible for the levels of NF-kB evident at any one time in any one cell.

NF-kB is found constitutively in the nucleus of some cells, particularly mature B cells. This suggests that it could play a role in the differentiation and activation of responses. Most complexes of NF-kB-related proteins have p50. Thus, a better under-standing of the process could be deduced by examining the consequences of deleting (knocking out) the gene for the p50 precursor. However, no developmental anomaly was evident in knockout animals, although the variety of response defects noted in knockout animals demonstrates an important role for p50 in mediating responses to infection. This is true despite the fact that genes for TNF-alpha and IL-1 are expressed normally after treatment of macrophages with bacterial lipopolysaccharide (LPS). Until the whole family of genes is knocked out, the complete range of NF-kB-controlled activities cannot be elucidated.

Studies on the Interactions of Superantigens With the Major Histocompatibility Complex (MHC) and the T-Cell Receptor (TCR)

Superantigens are powerful immunoregulatory molecules that are involved in a variety of diseases such as toxic shock syndrome. Two groups of super-antigens have been described: exogenous superantigens such as certain bacterial products, e.g., Staphylococcus enterotoxin B (SEB), and endogenous murine products that include MLS-like antigens (vSAG) produced by murine mammary tumor viruses (MMTV). Endogenous super-antigens govern the deletion of thymic T cells expressing certain Vß receptor molecules, whereas microbial antigens, which bind to class II MHC molecules, potently stimulate T cells. T-cell specificity for superantigen/MHC complexes is determined almost completely by the Vß element of the alphaß TCR, resulting in a very high frequency of responding cells. Mutational studies of SEB have identified residues important in MHC binding and in Vß interaction in the N-terminal 60 amino acids. Mutant toxins defective in either MHC binding or Vß interactions are non-toxic for mice in vivo but protect mice from challenge with wild type toxin. The C-terminal end of vSAG plays an important role in Vß interaction; antibodies to a C-terminal peptide can block T-cell stimulation.

Future Goals

The long-term objectives of the Immunology Boards are to elucidate the cellular and molecular mechanisms of the immune response and the pathogenesis of immunological disorders, to pursue areas of immunology needed to expedite vaccine development to prevent infectious diseases, and to pursue new methods to treat and prevent immunologic diseases. Although clinical immunology and its application to disease should receive greater emphasis, the basic immunology component is essential to understanding the pathogenesis of immunologic and infectious diseases. To advance these goals, the outstanding scientists of the Immunology Boards will continue their independent research on the molecular genetics and definition of the human genome, stem cells and hematopoiesis and the immuno-biology and genetic regulation of the MHC, the underlying mechanisms and genetic control of B-cell development, and the development of monoclonal antibody-based therapeutic strategies for the control of cancer. A major goal is the continued and joint participation of members of the Boards in exciting and productive scientific meetings with their counterparts.

Selected References

1. Ikuta K, Kina T, MacNeil I, Uchida N, Peault B, Chien YH, Weissman IL. A developmental switch in thymic lymphocyte maturation potential occurs at the level of hematopoietic stem cells. Cell 1990; 62:863-74.
2. Markowitz JS, Auchincloss H Jr, Grusby MJ, Glimcher LH. Class II-positive hematopoietic cells cannot mediate positive selection of CD4+ T lymphocytes in class II-deficient mice. Proc Natl Acad Sci USA 1993; 90:2779-83.
3. Oettinger MA, Schatz DG, Gorka C, Baltimore D. RAG-1 and RAG-2, adjacent genes that synergistically activate V(D)J recombination. Science 1990; 248:1517-23.
4. Shinkai Y, Koyasu S, Nakayama Murphy KM, Loh DY, Reinherz EL, Alt FW. Restoration of T cell development in RAG-2-deficient mice by functional TCR transgenes. Science 1993; 259:822-5.
5. Wang K, Klotz JL, Kiser G, Bristol G, Hays E, Lai E, Gese E, Kronenberg M, Hood L. Organization of the V gene segments in mouse T-cell antigen receptor alpha/delta locus. Genomics 1994; 20:419-28.

1. Kamikawaji N, Fujisawa K, Yoshizumi H, Fukunaga M, Yasunami M, Kimura A, Nishimura Y, Sasazuki T. HLA-DQ restricted CD4+ T cells specific to streptococcal antigen exist in low responders but not in high responders. J Immunol 1991; 146:2560-7.
2. Murakami M, Tsubata T, Okamoto M, Shimizu A, Kumagai S, Imura H, Honjo T. Antigen-induced apoptotic death of Ly-1 B cells responsible for autoimmune disease in transgenic mice. Nature 1992; 357:77-80.
3. Azuma M, Ito D, Yagita H, Okumura K, Philips JH, Lanier LL, Somoza C. B70 antigen is a second ligand for CTLA-4 and CD28. Nature 1993; 366:76-9.
4. Yanagida T, Kato T, Igarashi O, Inoue T, Nariuchi H. Second signal activity of IL-12 on the proliferation and IL-2R expression of T helper cell-1 clone. J Immunol 1994; 152:4919-28.
5. Akira S, Nishio Y, Inoue M, Wang X, Wei S, Matsusaka T, Yoshida K, Sudo T, Naruto M, Kishimoto T. Molecular cloning of APRF, a novel IFN-stimulated gene factor 3 p91-related transcription factor involved in the gp130-mediated signaling pathway. Cell 1994; 77:63-714.