Expanding Immunology: defensive versus ecological perspectives

Defending Lifeis one of the few serious efforts to understand the science of immunology theoretically by employing both scientific and philosophical critiques. Elling Ulvestad expertly summarizes diverse and extensive immunological science and then offers an ecologically inspired critique, which employs classical philosophical approaches as well as contemporary philosophy of science. His basic thesis is that the immune system functions within a larger context than the restricted confines of a circumscribed "self " opposing dangerous non-self challenges. That dichotomy of self and other would be replaced with a fully ecological orientation, in which immunity is characterized within a framework that includes the organism and its environment in terms of both defensive and cooperative functions. In other words, beyond characterizing immune reactions within the organism, immunology must also situate (contextualize) those responses within the larger environment in which they occur. Assembling a wide range of experimental findings and examining the models that structure them, Ulvestad presents both scientific and philosophical arguments to buttress his theoretical claims.

Because of the demands on the reader to bridge the scientific portrait of the immune system with a deep conceptual analysis, I fear Defending Life will have a small readership. That would be a pity. This book is not only an important contribution towards understanding the restrictions under which immunology now functions, but it provocatively suggests how the discipline might reorient itself to address more effectively not only the molecular mechanisms of immune reactions, but also their regulation and organization. And in a broader intellectual sense, this book represents a propitious step towards the full adoption of immunology by philosophy of biology as a member in good standing. These assertions require a rather detailed explanation, which begins with outlining the theoretical paradigm that has dominated 20th-century immunology, followed by a description of an ecologically driven notion of systems biology applied to modeling immune behavior, and finally a brief discussion of the underlying conceptual issues at stake in this shift in immunology's theoretical orientation.

In meeting the criticism of a circumscribed selfhood as the theoretical formulation of immunology's theory, an "ecological immunology" would expand the context of immune behaviors and place immunobiology fully within a true systems characterization. Such an approach presumably will push immunology towards a larger ecological conceptualization for understanding immune regulation and thus expand contemporary immunological theory well beyond its current borders, where defense of singular selves is replaced with models describing the interactions of individuals in a community of others.

Background

Our current understanding of immunity began in the 1890s with the recognition that microbes caused infectious diseases. Those discoveries were coupled to dramatic experiments demonstrating the body's active response to such insults. Indeed, the debut Nobel Prize in Medicine in 1901 was awarded to Emil von Behring for the first successful immune-based therapy against diphtheria (Linton 2005). Immunology became the Great Promise, and by 1908, half of the medicine Nobel laureates were selected on the basis of their having elucidated infectious diseases and the immune mechanisms responsible for their control. Contemporary research continues to focus on elucidating the immune responses to infectious agents, and the mechanisms of pathogen control within the context of the evolution of those relationships dominates immunology's theoretical considerations (Frank 2002). One of the strengths of Defending Life is its sweeping, yet comprehensive review of the evolutionary mechanisms that have molded the immune system in the context of pathogenic pressures.

This defensive framework has guided experimental and theoretical immunology for the past century, so that the current consensus holds that the immune system evolved to provide defense to a susceptible host—the self—and that immunology is the scientific study of self/non-self discrimination. The story of how Sir Macfarlane Burnet introduced the "immune self" concept in 1949 (Burnet and Fenner 1949) has been detailed elsewhere (Crist and Tauber 2000; Tauber 1994a); here it suffices to note that the implicit notion of the self became explicit as a guiding model of immune theory by the 1970s (Podolsky and Tauber 1997;Tauber 1994b, 2004). However, concomitant with the acceptance of this dichotomy of self and other, by the...