Genetics and immunology

T cell Tolerance in Early Life

T cell-mediated immune tolerance is a state of unresponsiveness of T cells towards specific self or non-self antigens. This is particularly essential during prenatal/neonatal period when T cells are exposed to dramatically changing environment and required to avoid rejection of maternal antigens, limit autoimmune responses, tolerate inert environmental and food antigens and antigens from non-harmful commensal microorganisms, promote maturation of mucosal barrier function, yet mount an appropriate response to pathogenic microorganisms. The cell-intrinsic and cell extrinsic mechanisms promote the generation of prenatal/neonatal T cells with distinct features to meet the complex and dynamic need of tolerance during this period. Reduced exposure or impaired tolerance in early life may have significant impact on allergic or autoimmune diseases in adult life. The uniqueness of conventional and regulatory T cells in human umbilical cord blood (UCB) may also provide certain advantages in UCB transplantation for hematological disorders.

Current status and future directions of cancer immunotherapy

In the past decades, our knowledge about the relationship between cancer and the immune system has increased considerably. Recent years' success of cancer immunotherapy including monoclonal antibodies (mAbs), cancer vaccines, adoptive cancer therapy and the immune checkpoint therapy has revolutionized traditional cancer treatment. However, challenges still exist in this field. Personalized combination therapies via new techniques will be the next promising strategies for the future cancer treatment direction.

The Role of Tumor Microenvironment in Cancer Immunotherapy

The field of tumor immunology and immunotherapy has undergone a renaissance in the past decade do in large part to a better understanding of the tumor immune microenvironment. After suffering countless successes and setbacks in the twentieth century, immunotherapy has now come to the forefront of cancer research and is recognized as an important tool in the anti-tumor armamentarium. The goal of therapy is to aid the immune system in recognition and destruction of tumor cells by enhancing its ability to react to tumor antigens. This traditionally has been accomplished by induction of adaptive immunity through vaccination or through passive delivery of immunologic effectors as in the case of adoptive cell transfer. The recent discovery of immune "checkpoints" whose purpose is to suppress immune activity and prevent auto-immunity has created a new angle by which reactivity to tumors can be enhanced. Blockers of these checkpoints have yielded impressive clinical results and have recently been approved for use in a wide variety of malignancies. With data showing increasing rates of not only treatment response, but complete remissions, immunotherapy is poised to become an increasingly utilized therapy in the treatment of cancer.

Neonatal tolerance: applicability to solid organ transplantation

PURPOSE OF REVIEW

The phenomenon of tolerance induced during immunologic immaturity has been explored for more than 60 years. Although direct application of neonatal tolerance to organ transplantation in human newborns is limited, exploiting discrete components of neonatal immaturity is proving fruitful.

RECENT FINDINGS

Two reviews comprehensively considered features and impact of neonatal tolerance as described in the 1950s. Recent imaging studies in mice demonstrated complex functional interactions especially of donor regulatory T cells with emerging neonatal immune components. The propensity of the developing immune system toward tolerance rather than immunity to non-self carbohydrates in ABO-incompatible transplantation was shown using glyconanotechnology tools to have exquisite specificity, and is associated with age-related changes in the B-cell compartment and complement components. Discarded infant thymus was found to be a source of abundant therapeutic regulatory T cells. Erythroid precursors transiently present in newborn mice and humans were shown to have immunosuppressive properties that may contribute to a tolerogenic environment.

SUMMARY

Neonatal tolerance has profound impact on immunology well beyond transplantation. Continued exploration of mechanisms underlying the malleability of the developing immune system and exploitation of particular components are leading to tools for immune manipulation beyond infancy.

Immune balance: the development of the idea and its applications

It has long been taken for granted that the immune system's capacity to protect an individual from infection and disease depends on the power of the system to distinguish between self and nonself. However, accumulating data have undermined this fundamental concept. Evidence against the self/nonself discrimination model left researchers in need of a new overarching framework able to capture the immune system's reactivity. Here, I highlight that along with the self/nonself model, another powerful representation of the immune system's reactivity has been developed in the twentieth century immunology. According to this alternative view, the immune system is not a killer of nonself strangers but a peace-maker helping to establish harmony with the environment. The balance view of the system has never become part of the dominant paradigm. However, it is gaining more and more currency as new research develops. Advances in mucosal immunology confirm that instead of distinguishing between self and foreign the immune system reacts to microbial, chemical and self-induced alterations to produce responses that counterbalance effects of these changes.

Fashioning the immunological self: the biological individuality of F. Macfarlane Burnet

During the 1940s and 1950s, the Australian microbiologist F. Macfarlane Burnet sought a biologically plausible explanation of antibody production. In this essay, we seek to recover the conceptual pathways that Burnet followed in his immunological theorizing. In so doing, we emphasize the influence of speculations on individuality, especially those of philosopher Alfred North Whitehead; the impact of cybernetics and information theory; and the contributions of clinical research into autoimmune disease that took place in Melbourne. We point to the influence of local experimental and intellectual currents on Burnet's work. Accordingly, this essay describes an arc distinct from most other tracings of Burnet's conceptual development, which focus on his early bacteriophage research, his fascination with the work of Julian Huxley and other biologists in the 1920s, and his interest in North Atlantic experimental investigations in the life sciences. No doubt these too were potent influences, but they seem insufficient to explain, for example, Burnet's sudden enthusiasm in the 1940s for immunological definitions of self and not-self. We want to demonstrate here how Burnet's deep involvement in philosophical biology - along with attention to local clinical research - provided him with additional theoretic tools and conceptual equipment, with which to explain immune function.

[Uncertainties about the self and the issue of the proper theoretical model in immunology]

Theoretical immunology constitutes a critical basis of all medical discoveries. Immunology has been dominated since the 1940s by the self/nonself model. Here we try to shed light on the origins of this theoretical model and to show how and why this model has been called into question during the last thirty years. This paper has three aims. Firstly, we explore the sources of the immune self, going upstream from immunology to ecology-biology, psychology and eventually philosophy. Here the key questions : is the immune self really analogous with the philosophical and psychological selves in which it originates? What is the signification and adequacy of such a conceptual borrowing? We suggest that the << self >> vocabulary in immunology is not clear and precise. Secondly, we present the experimental inadequacies of the self/non-self model. We show then how both the vagueness of the term << self >> and these experimental flaws casted doubt on theories of immunology. Among the several models that have been proposed recently, none has attracted a consensus. Some immunologists have even suggested that immunology should rid itself of theorical concerns and concentrate on molecular aspects. This suggestion, however, is unacceptable\; hence it is still necessary to find a theoretical framework for immunology. Finally, we try to suggest a way to escape this uncomfortable situation of doubt. The immune << self >> and the immune << system >> (<< network >>) are rooted in strong metaphysical conceptions of identity, the main characteristic of which is to consider the organism as an enclosed and self-constructing entity. By contrast, based on experimental data about immune tolerance and host-pathogen interactions, we propose to consider organisms as open entities. To what theory does this conception lead? What would be the consequences of such a theory with regard to medical aspects?

If the immune repertoire evolved to be large, random, and somatically generated, then

The evolution of the somatically generated random combining site repertoire of the "adaptive" immune system depended on the concurrent appearance of a somatic process that sorted the repertoire into anti-self and anti-nonself. Unlike the germline-selected sorting process characteristic of "innate" defense mechanisms, somatic sorting of the repertoire requires that antigens be classified based on their behavior, not on their physical or chemical properties. As specific recognitive combining sites (paratopes) define antigenic determinants (epitopes), the sorting of the repertoire operates epitope-by-epitope. By contrast, the coupling of the paratope to effector function must operate antigen-by-antigen because the response to each epitope on the antigen must be in the same effector class (i.e., coherent). This distinction resolves a long standing debate and provides a basis for analyzing the various models.

Historical vignette: a life with poxviruses and publishers

Although I started science investigating the physical anthropology of Australian aboriginals and then spent six years in the Australian Army during the 1939-45 war, largely working on malaria control, the poxviruses have been the focal point of my research--at the bench, in the field, on committees, and in front of my word processor. I have had a relatively short period as a scientist at the bench, just over twenty years out of the sixty years since I graduated. For the last thirty years the pipette has been replaced by the pen and the word processor, and contacts with publishers have become an important element in my life. My pilgrim's progress, from mousepox through myxomatosis to vaccinia and then smallpox, has been helped by what can only be described as good luck, coming in many guises. I have been fortunate in many ways; in my father and mother and the genes and family life they gave me; in my wife, who was an immense source of support until her death in 1995; in the people whom I met during the Second World War; and in my close association with three great scientists, Macfarlane Burnet, René Dubos, and Howard Florey. I had the good fortune to be appointed, as a young and inexperienced virologist, to one of the best research jobs in the world, as a professor in the Australian National University. I have been very lucky in having had the opportunity to exploit a series of scientific gold mines; in turn, malaria, during the War, then mousepox, an unexploited virus because its use was forbidden in the United States, then, after a brief flirtation with mycobacteria, myxomatosis, an unparalleled natural experiment of evolution in action, and finally the most impressive achievement in public health in world history, the global eradication of smallpox. My last job in the University before retirement provided me with the opportunity to do something about the most important problems confronting humankind: the degradation of the environment, driven by the explosion in human numbers and their ever-growing use of resources. Each of these activities has provided opportunities to establish and maintain close friendships with scientists all over the world.

Relationships among interaction products in hybrids between pigeons and doves, following transfer of genes between species

Following the transfer to the common pigeon (Columba livia) of a cellular antigen (Cg) fromC. guinea, and toStreptopelia risoriaof respective members of the group-8 system fromchinensisandsenegalensis, new combinations of these two antigenic systems were produced from matings ofliviaandrisoria. The hybrid substances associated with the cells of each of the five new combinations of the cellular antigens were related to each other and to the usual F1-livia/risoriacells but, with the possible exception of two, were definitely differentiated from each other. Cross-reactivities of the reagents for the hybrid substances were also observed, primarily with heterozygotes of the group-8 system ofStreptopelia. Evidence is thus provided that the interaction takes place primarily if not entirely between the genes of the C-system ofColumbaand the group-8 system ofStreptopelia.