LIST OF PLATES FRONTISPIECE: MEDAL STRUCK FOR THE FIRST INTERNATIONAL CONGRESS OF IMMUNOLOGY, WASHINGTON D.C. 1971 1. JULIUS COHNHEIM'S GROUP AND VISITORS, BRESLAU, 1877 2. EHRLICH IN BERLIN, ABOUT 1 890 3. ROBERT KOCH 4. EMIL BEHRING 5. THE ROYAL INSTITUTE FOR EXPERIMENTAL THERAPY, FRANKFURT, 1900 6. EHRLICH AND SVANTE ARRHENIUS 7. JULES BORDET 8. EHRLICH AND ASSOCIATES, ABOUT 1 903 9. EHRLICH IN 1 910 lO. EHRLICH'S GRAVESITE, FRANKFURT AM MAIN 1 1. ONE OF EHRLICH'S FAMOUS BLOKE 12. EHRLICH'S LAST PORTRAIT, 1915 13. EHRLICH'S OFFICE IN FRANKFURT, FEBRUARY 26, 1914 14. COLLECTION OF EHRLICH'S MEDALS AND HONORS Plates appear after page 94 INTRODUCTION In this age of complex and wonderfully powerful technologies, it is easy to for get that scientific research is primarily about ideas. The fact that science is also about numbers, as Max Delbriick insisted, is somewhat less obvious. The best sci entists build their experiments around an exciting hypothesis, using solid tech niques and strict quantitation. A few carry a dominant infusing paradigm from one problem to others, fertilizing several research areas. A very few indeed reach the pinnacle again and again; for them we reserve the term genius and from them we must learn. A tiny handful achieve such luster as to outlive their era and shine on into history. One such, indubitably, is Paul Ehrlich. For this reason, a penetrat ing and sensitive analysis of his work is a major intellectual event. All serious observers of the triumphant scene that is modern immunology should therefore be very grateful to the distinguished immunologist and historian Dr. Arthur M. Sil- verstein for describing so clearly Paul Ehrlich's "magificent obsession." Most immunologists would know Paul Ehrlich for three things: the introduc tion of quantitative methods into the study of antibodies and antigens; the side- chain theory, which was the distant forerunner of clonal selection; and the dis covery of Salvarsan. Silverstein indeed summarizes and discusses these admirably, but he does much more. He places them into an unbroken chain of research, showing us wonderful work spanning a full 38 years. Furthermore, he reveals that a single preoccupation provided the thread linking quite disparate research endeavors, namely that biological processes depend on the interaction between a substance and a preformed receptor—an interaction that was specific and depended on stereochemical fit. Ehrlich remained faithful to this paradigm all his life. XII INTRODUCTION We learn about Ehrlich's early work on staining reactions of tissues with dyestuffs, a chemistry-rich M.D. thesis in which the seeds of the idea of biologi cal specificity are already apparent. This interest leads to the development of techniques to stain blood cells, with Ehrlich identifying basophils, eosinophils, and neutrophils. The basis is the staining of the granules of these polymorphonu clear leukocytes with basic, acidic (eosin being the typical one), or neutral dyes. The great Max Wintrobe therefore recognized Ehrlich as one of the fathers of modem hematology. Ehrlich also discovered how best to stain Koch's tubercle bacillus and briefly worked on tuberculin. Much more significant studies, how ever, were those on the plant toxins, ricin and abrin, in which Ehrlich first demon strated his ability to introduce rigorous quantitation into immunity research—that is, the standardization of toxin activities and of antibody strength. These predated the work of Behring and Kitasato on the treatment of diphtheria by the passive injection of antitoxin antisera from various animals. It was logical and relatively simple for Ehrlich to apply the knowledge gained via the plant toxin system to the urgent questions of how to produce very high-titred sera and how to standardize the doses used in treatment. It was really Ehrlich's clinical trials that proved the value of Behring's discovery, which had previously been bedevilled by inconsis tent and variable results. Furthermore, in the plant toxin studies, Ehrlich had essentially solved the problem of transfer of antibodies from mother to infant, showing that this involved both transplacental transport and passage of antibodies via the milk. Thus, he was in a position to use goat and cow milk as an alternative to serum as a source of antitoxin. This approach appears not to have been fol lowed actively, and soon horse serum became the standard clinical tool, ruling the therapy of diphtheria for 30 years. Then, diphtheria toxoid was perfected and active immunization gradually took over. The nature of the antigen-antibody interaction preoccupied Ehrlich greatly. Even famous men make mistakes. Thus, Ehrlich argued with Svante Arrhenius about the reversibility of the reaction, claiming that when antigen and antibody met, a chemical reaction akin to covalent bonding took place. Of course, in many situations that Ehrlich encountered, the bivalence (or multivalence) of antibodies made the reaction operationally irreversible. Ehrlich was also wrong in his argu ment with Jules Bordet about complement, claiming that immune hemolysis could not be explained without a multiplicity of complements. Dr. Silverstein produces a fascinating insight into Ehrlich's mind as he takes us through the elab orate contortions of theorizing, ad hoc argument piled on ad hoc argument, because of course Ehrlich thought that he was always right. In no area was this self-confidence more apparent than in Ehrlich's side-chain theory. This held that antibodies were specific receptors on the cell surface, which preexist as natural molecules. When the antigen (e.g., a toxin) enters the body, it combines in a stereospecific manner with the receptor and neutralizes it, thus set ting up a process whereby the body needs to make up for the deficiency by form ing more receptors. With further injection of antigen, the process overshoots and excess natural antibodies spill into the serum. Silverstein sees the pictorial form INTRODUCTION XIII of this theory, as presented in 1900 in EhrHch's Croonian Lecture of the Royal Society, as epitomizing his magificent obsession and also as having been particu larly influential. This side-chain theory was the crowning glory of Ehrlich's excursion into immunology. After 1901, his fertile mind and active laboratory research turned elsewhere. Although Ehrlich's work on cancer, using various transplantable tumor mod els, was not particularly successful, his shift in 1905 into the chemotherapy of various infectious diseases provided the last glorious chapter of this remarkable scientific life. He used screening techniques and chemical modifications of promising compounds to attempt to find the "magic bullets" capable of killing pathogens while leaving the host unharmed. In June 1909, EhrHch's faithful asso ciate Sahashiro Hata, recently arrived from Japan, tested compound number 606 in a variety of infections. It soon proved capable of curing syphilis, and, with the drug christened Salvarsan, the modem era of scientific pharmacology was ush ered in. Had he lived long enough, Ehrlich would surely have won a second Nobel Prize for this feat. Silverstein concentrates on giving us a full and satisfying insight into Ehrlich's scientific oeuvre. He succeeds admirably in guiding us into looking at the various problems with the mindset of Ehrlich's times. He avoids going into details of Ehrlich's personal life except to the extent that Ehrlich the scientist is naturally influenced by Ehrlich the man. Chapter 9 is of particular interest as it explores Ehrlich's scientific style. Silverstein develops the theory that all Ehrlich's work rests on a single precept, namely the interaction of agonists with preformed recep tors. But we learn much more than this. We gain insight into Ehrlich's tempera ment, his character, his leadership qualities, his interactions with scientific col leagues, indeed his Weltanschauung. Those of us who have known Art Silverstein for many decades and have admired his contributions to his chosen branch of immunology wondered greatly about the increasing time he was spending since the late 1970s on the history of immunology. We saw a first vindication in his excellent 1989 work A History of Immunology. Now we have a further and most welcome dividend in the present extraordinary book, a work of scholarship, a labor of love, in fact an obsession in its own right. The book will enrich the wide readership it will surely receive. We can only hope that its certain success will stimulate further projects. Our past leaders still have so much to teach us! G.J.V.Nossal Melbourne December, 2000 PREFACE In 1989,1 finished A History of Immunology.^ It had taken 11 years of part-time activity stolen from my research laboratory obligations—obligations owed both to the Independent Order of Oddfellows who had endowed my Chair and to the National Institutes of Health who financed my research. The writing of the book proved so fascinating, and the book was so well received, that I felt that I must do another historical work in immunology. But 11 years was too long, and I no longer felt free to shortchange my laboratory research, so that I opted to retire from the lab oratory to the Welch Medical Library, where Gert Brieger generously let me have a small office in the Johns Hopkins Institute for the History of Medicine. Why should it have taken 11 years to write a general history of immunology, and especially one that did insufficient justice to such areas as allergy, comple ment, and natural immunity, and that stopped short of the startling developments that accompanied the immunobiological revolution of the late 1960s and 1970s? Much of the answer lay in the dearth of secondary literature in this field; up to that point, not many historians (or even immunologists) had written analyses of the events of the past that might have provided shortcuts to an understanding of the contributions of individuals, of the bases for scientific disputes, or of the reasons why some ideas succeeded and others failed. Thus, one had perforce to depend largely on the original literature and an one's own interpretations, hoping that one had covered the writings fully and interpreted correctly both their literal meaning and the between-the-lines implications. Now, some 10 to 20 years later, the field of historical studies in immunology has attained a certain status among the subdisciplines of the history of the bio medical sciences. A critical mass of investigators now exists, including book authors Anne-Marie Moulin,^ Alfred Tauber,^ Pauline Mazumdar,"^ Tatyana XV XVI PREFACE UFyankina,^ and Leslie Brent;^ collections edited by Deborah Jan Bibel,'^ Gilberto Corbellini,^ Mazumdar,^ and Richard Gallagher et al.;^^ and numerous papers by these authors as well as by Alberto Cambrosio and Peter Keating, liana Lowy, Craig Stillwell, and Nicholas Rasmussin. In addition, several journals now give occasional space to historical contributions,^^ or to the reminiscences of elder-statesmen immunologists.^^ History of Immunology workshops were held at the International Congresses of Immunology at Toronto, Berlin, and Budapest, where interested individuals exchanged views on important events in the history of immunology. Finally, the past few years have seen a number of international symposia on the subject. ^^ Thus, one may safely conclude that the history of immunology has come of age. During several years of research around the periphery of immunological his tory,^'* I cast around for a major project to occupy my time and interest. I remem bered having described in my book the proximate stimulus for my entrance into the history of immunology ^^—the story of a manuscript I was given to review for The Journal of Immunology on the maternal transfer of antibody to the neonate by a 1970s author, who failed to mention that Paul Ehrlich had done the same study and obtained substantially the same results 80 years earlier. I went back to reread Ehrlich's papers^^ and found them truly remarkable! Not only had Ehrlich in 1892 solved the problem of maternal-fetal transfer of antibody in utero and of maternal-neonatal transfer via the milk—devising for the purpose some of the most elegant experiments of the 19th century ^^—but in one of the papers he had actually defined the kinetics of the primary and booster antibody responses. This work would not be improved on for a further 80 years. Surely this work should have been more widely known, if not from the original reports then certainly from one of the many biographies of Paul Ehrlich. As I read through these biographies, it became apparent that neither in that of his adoring secretary,^^ nor in those of his admiring students or later celebrants of his fame^^ were the details of this extraordinary work to be found. Indeed, many of them did not even mention the pediatric studies at all. As I examined other of Ehrlich's immunological research, I found the same lack of attention in the biographies to the fine and important details of Ehrlich the scientist. Nowhere was it made clear why he had embarked on a given set of immunological studies, nor was attention drawn to their precision and elegance. There was little elaboration of the details of Ehrlich's results or of their exact significance both contemporaneously and during the long-term development of the field of immunology. Only in two places does one find at least an attempt to explore the minutiae of Ehrlich's science. In Claude Dolman's treatment of Ehrlich in The Dictionary of Scientific Biography,^^ most of his important studies are mentioned, but not in great detail. Only in the Festschrift for Ehrlich's 60th birthday^i did his more famous colleagues and students come close to detailing Ehrlich's experiments and their significance, and even many of these summaries are incomplete. But even incomplete, this Festschrift had never been translated from its original Ger man, and thus is essentially unavailable to most modern scientists (and even to PREFACE XVII many modem historians). Indeed, many of Ehriich's other important studies (e.g., the ricin/abrin work; the matemal-fetal/neonatal experiments) were not even deemed important enough to be included in the 1904 Collected Studies in Immu- nityP- or to have been translated in the three-volume collection of Ehriich's works put together in 1957 by Dr. Fred Himmelweit of St. Mary's Medical School. Lon don, under the supervision of Sir Henry Dale.^^ Here was my project, clearly defined. I would attempt to provide the details and an interpretation of Ehriich's immunological studies, segment by segment. For each of the immunological areas in which he worked, I would attempt, where possible, to indicate why he undertook the studies (i.e., the contemporary con text), how he did the experiments (the experimental design), what results he obtained, and, as best I am able, the significance of his results, both contemporary and in the long term. Given the publication habits of 19th-century scientists, and especially the occasional turgidity of Ehriich's scientific prose, I have taken cer tain liberties in recasting his results and adapting his data tables into a form more understandable, perhaps, to modern readers. I decided, further, that I would deal only with Ehrlich the scientist, and leave Ehrlich the man to others. But it quickly became apparent that the "scientist" is frequently influenced by the "man." When we see Ehrlich jealous of his discover ies and fighting an Arrhenius or a Gruber against their attacks on his position,^^ or an Ehrlich so imbued by a sense of logic that he builds logically consistent but otherwise improbably complicated ad hoc structures to integrate new data into old theories (as he did to explain toxin-antitoxin neutralization curves^^ or the multiplicity of complements^^), then aspects of the man emerge as well. To the extent that these traits are discernible in Ehrlich, they will be commented on in the last chapter on Ehriich's scientific style. To fully explain Paul Ehriich's ideas, and especially why some of them have not survived the test of time, poses a curious historiographic challenge. Historians consider it a sin {cdiWtdipresentism) to bring modern knowledge to bear when dis cussing historical data and its interpretation. If an Ehrlich 'misinterpreted' some results because he could not have known at the time of the existence of some interfering substance or process, this should not be held to reflect on his intelli gence or competence. However, the modem reader (and especially the expert in that field) deserves to be told what it was that actually produced the misleading results, so that the reader may fully understand the experimental system, the data it produced, and thus why the historical interpretation was so reasonable. This situation arises several times in the discussions of Ehriich's work, most particularly in his (and others') studies of "anti-antibodies" and "anti-comple ments." In each instance, I will attempt fairly to explain why Ehrlich interpreted his data in a certain way and why, knowing what he did, the interpretations appeared to be both reasonable and logical. I will then point out what Ehrlich could not have appreciated at the time: the presence of unrecognized reagents and interactions that skewed the results to provide a false trail to the tmth. This XVIII PREFACE approach will, I hope, avoid the danger of seeming to judge Ehrlich using modern knowledge, while serving well the needs of the modem reader.^^ I owe a strong debt of gratitude to many individuals whose assistance helped to smooth an otherwise problem-strewn path. Foremost among these is Gunther Schwerin, last surviving grandson of Paul Ehrlich, whose recent untimely death is much regretted by his many admirers. Schwerin's friendship and enthusiastic sup port were invaluable; he not only sent me direcdy much important material on Ehrlich, but he provided me with an entry to the large collection of Ehrlich papers that he had deposited at the Rockefeller University Archives Center at Tarrytown, New York. He also established a fund there to support research on his grandfa ther's papers, from which I received a grant to defray the travel expenses incurred on many visits to the Archives Center. I acknowledge also the encouragement of Mrs. Elizabeth Brody, great-granddaughter of Paul Ehrlich, who has also gener ously supported the translation of many of Ehrlich's papers and of the Festschrift published in 1914 in honor of Ehrlich's 60th birthday. At the Rockefeller Archives Center, I appreciated greatly the help of Dr. Dar win Stapleton, director of this well-equipped and well-organized institution, and of Dr. Lee Hiltzik, its archivist. I must also express my appreciation to Dr. Eliza beth Fee and the staff of the History of Medicine Division at the National Library of Medicine in Bethesda, Maryland, for their help in consulting their rich resources. I have also received valuable help from several others interested in Paul Ehrlich, notably Professor Dr. Hans Schadewaldt of Diisseldorf, Professor A. Thomas Stoeckl of Freiburg, Dr. Bemhard Witkop of Bethesda, and Grafin Suzanne von Goertz of Munich. I learned much about the arcana of immunological history from extensive dis cussions with Anne-Marie Moulin, Alberto Cambrosio and Peter Keating, Alfred Tauber, Noel Rose, and many others. I learned about problems of biography from Thomas Soderqvist (although we have agreed that what follows is not a biogra phy; neither is it a hagiography). In the area of historiographic practices, I owe much to Gert Brieger, Harry Marks, Daniel Todes, Owsei Temkin, and Edward Morman for many instructive discussions. NOTES AND REFERENCES 1. Silverstein, A.M., A History of Immunology, New York, Academic Press, 1989. 2. Moulin, A.-M., Le Dernier Langage de la Medicine: Histoire de VImmunologic de Pasteur an SIDA, Paris, Presse Universitaire, 1991. 3. Tauber, A.I., and Chemyak, L., Metchnikoff and the Origins of Immunology, New York, Oxford Uni versity Press, 1991; Tauber, A.I., The Immune Self Theory or Metaphor?, Cambridge, Cambridge University Press, 1994; Tauber, A.I. and Podolsky, S.H., The Generation of Diversity: Clonal Selec tion Theory and Rise of Molecular Biology, Cambridge, Harvard University Press, 2000. 4. Mazumdar, P.M.H., Species and Specificity: An Interpretation of the History of Immunology, New York, Cambridge University Press, 1995. 5. Ul'yankina, T.I., Zarozhdeniye Immunologii [The Origins of Immunology], Moscow, Nauka, 1994. PREFACE XIX 6. Brent, L., A History of Transplantation, London, Academic Press, 1997. 7. Bibel, D.J., Milestones in Immunology, New York, Springer, 1984. 8. Corbellini, G., ed., L'Evoluzione del Pensiero Immunologico, Torino, Bollati Boringhieri, 1990. 9. Mazumdar, P.M.H., Immunology 1930-1980, Toronto, Wall & Thompson, 1989. 10. Gallagher, R.B., Gilder, J., Nossal, G.J.V., and Salvatore, G., eds.. Immunology: The Making of a Modern Science, New York, Academic Press, 1995, 11. For example. Cellular Immunology, Immunology Today, and Nature-Immunology. 12. For example. Annual Reviews of Immunology, Immunology Today, and Annual Reviews of Bio chemistry. 13. Thus, L'Institut Pasteur: Contributions a son Histoire, M. Morange, ed., Paris, La Decouverte, 1991; Immunology: Pasteur's Heritage, P.-A. Cazenave and G.P. Talwar, eds.. New Delhi, Wiley Eastern, 1991; "Immunology as a Historical Object," J. Hist. Biol. 27(3): 1994; Singular Selves: Historical Issues and Contemporary Debates, A.-M. Moulin and A. Cambrosio, eds., Paris, Else vier, 2001; see also Hist. Philos. Life Sci. 22(1): 2000. 14. Thus, "Ocular Immunology: On the Birth of a New Discipline," Cell. Immunol. 136:504, 1991; "The Pasteur Institute and the Advent of Immunology: The Great Immunological Debates," in: P- A. Cazenave and G.P. Talwar, eds., Immunology: Pasteur's Heritage, Wiley Eastern Ltd., New Delhi, 1991, pp. 11-20; "The Structure and Dynamics of Immunology, 1951-1972: A Prosopo- graphical Study of International Meetings," Cell. Immunol. 158:1, 1994; and "The Heuristic Value of Experimental Systems: The Case of Immune Hemolysis," /. Hist. Biol. 27:437, 1994. 15. A History of Immunology, note 1, pp. xi-xii. 16. Ehrlich R, Z Hygiene 12:183-203, 1892; Brieger L. and Ehrlich R, Deutsch. med. Wochenschr. 18:393,1892; Brieger L. and Ehrlich P, Z Hyg. 13:336, 1893; Ehrlich P and Hiibener W., Z Hyg. 18:51, 1894. 17. These experiments are described in Silverstein, A.M., Nature Immunol. 1:93, 2000. 18. Marquardt, M., Paul Ehrlich als Mensch undArbeiter, Stuttgart, Deutsche Verlags Anstalt, 1924 (English ed., Paul Ehrlich, London, William Heinemann, 1949). 19. Lazarus, A., "Paul Ehrlich," in M. Neuberger, ed., Meister der Heilkunde I, Vienna, Rikola, 1922, pp. 9-88; Loewe, H., "Paul Ehrlich. Schopfer der Chemotherapie," in Grosse Naturforscher VIII, Stuttgart, Wissenschaftlicher Verlagsges., 1950; Venzmer, G., Paul Ehrlich, Leben und Werken, Stuttgart, Mundus, 1948; Satter, H., Paul Ehrlich, BegrUnder der Chemotherapie, 2nd ed., Munich, Oldenbourg, 1963; Greiling, W, Paul Ehrlich. Leben und Werk, Dusseldorf, Econ Ver- lag, 1964; Baumler, E., Paul Ehrlich: Scientist for Life, New York, Holmes & Meier, 1984. 20. Dolman, C, "Paul Ehrlich," in Dictionary Sci. Biog. 4:295-303. 21. Apolant, H., ed., Paul Ehrlich: Eine Darstellung seines wissenschaftlichen Wirkens, Jena, Gustav Fischer, 1914. This will be referred to henceforth as the Ehrlich Festschrift. 22. Ehrlich, P., Gesammelte Arbeiten zur Immunitdtsforschung, Berlin, Hirschwald, 1904; English trans, by C. Balduan, Collected Studies in Immunity, New York, Wiley & Sons, 1906. 23. Himmelweit, F, ed., The Collected Papers of Paul Ehrlich, 3 vols., London, Pergamon, 1957-1960. There was to have been a fourth volume, but an extensive search has failed to reveal why it was never pubUshed. See Silverstein, A.M., Bull. Hist. Med. 75 No. 3, 2001. 24. A History of Immunology, note 1, p. 103 ff. 25. A History of Immunology, note 1, p. 97. 26. A History of Immunology, note 1, pp. 103 and 196. 27. I find moral support for this position in Nick Jardine's discussion of the uses and abuses of anachronism in writing the history of science (Hist. Sci. 38:251, 2000). He points out that if the intent is to understand what the historical figure meant, then "vicious anachronism" is a no-no; if, however, the intent is to explain a modem outcome, then there is "legitimate use of anachronism in the service of explanation and critique of past activities and products of the sciences" (p. 266). 1 T HE BACKGROUND TO E H R L I C H 'S IMMUNOLOGY: O R I G I NS OF T HE RECEPTOR THEORY ...the sidechain theory was laid down fixed and finished in the Sauerstoffbedurfnis [1885], at a time when there was not yet an immunology. Leonor Michaelis^ It is undoubtdly rare that the general concept underlying a major breakthrough in the biological sciences should have arisen suddenly and fully formed, like Athena from the forehead of Zeus. More often, it is the slow accretion of many varied facts that leads to a formulation that is tested and retested, each time slightly modified, until a mature system of thought is acknowledged and made explicit. So it was, among others, with Darwin's theory of evolution and with Vir- chow's cellular pathology; so also was it with Paul Ehrlich's side-chain receptor theory of antibody formation. Thus, the epigraph by Michaelis, written in 1914 for the celebration of Ehrlich's 60th birthday,^ was his attempt to show that Ehrlich's theory had grown on an earlier rootstock. But only five years later, Michaelis would unearth Ehrlich's long-lost thesis for his M.D. degree,^ entitled Contributions to the The ory and Practice of Histological Staining,^ written in 1878. The discussion of the mechanism of staining by this 24 year old put back to an even earlier date the germination of the theory that would guide him in all of his future scientific endeavors. We shall return to these two major contributions in due course, but only after discovering that the seeds of his chemically based receptor theory had been planted even earlier than this. To repeat the caveat mentioned in the pref ace, we shall examine Ehrlich's early science in detail, to look for the founda tions of the theoretical system that he would apply so productively to so many