By fashioning such variability into antibodies, nature has also created the potential for exquisite specificity and variability.6 The enormous diversity can allow antibodies to recognize and interact with virtually any molecule found in nature. Indeed, the ability to recognize foreign molecules extends beyond what is found in nature. For example, exposure to man-made chemicals such as asbestos can elicit responses from certain antibodies in the body.
Once an antibody seeks out a molecule of interest, it can deploy a variety of different means to kill or neutralize its target. In some cases, the mere act of binding can disrupt the target. Antibodies, from the perspective of a cell, are rather large. The size of such very small things is measured using a term known as a Dalton (so-named to honor the memory of John Dalton, a 19th-century chemist). To put things in proper perspective, a typical hydrogen molecule weighs one Dalton, and a medicine such as aspirin weighs something like 180 Daltons. Compare these relatively small molecules with the comparatively heavy weight of an antibody at 150,000 Daltons, with some clocking in at more than 900,000 Daltons. As such, one can see why the sudden attachment of a large hunk of antibody onto a protein or sugar molecule can be sufficient to disrupt its function.
In other cases, an antibody binding to a foreign target can recruit other components of the immune system. Whereas we already discussed that two of the highly variable arms of a Y-shaped antibody bind the antigen, the third arm (known as a constant fragment, or Fc) can bind other components of the host defense system. One example is a structure know as an Fc receptor, which is conveniently found on the surface of many cell-killing cells of the immune system. If the antibody is bound to an antigen on a bacterium and then comes into contact with the Fc receptor on a macrophage (a killer cell), for example, the macrophage is triggered to engulf the antibody-antigen complex. If that complex happens to be a live bacterium—a preferred quarry of macrophages—then certain enzymes in the macrophage are alerted and go in for the kill, which generally shatters the intruder into many pieces. The macrophage then takes these pieces and shows them off to other immune cells (the T cells) to alert the wider immune system to the presence of the interloper.
The binding of an antibody to a foreign target can alternatively trigger a series of chemical reactions involving proteins that evolved many millennia before the first antibody. This collection of proteins, known as the “complement cascade,” entails a version of the toxin-antitoxin system described in chapter 3 (though not to be confused with the use of the term antitoxin that will be used in this chapter). Returning to the example of an antibody bound to the surface of a bacterium, this binding might trigger the coordinated assembly of a structure that alerts the immune system early on to the presence of a foreign invader while also creating a hole in the membrane of the bacterium. This hole causes the bacterial entrails to leak out, thereby eliminating unwanted germs. Given this potent killing power, both the Fc-mediated engulfment and complement systems have multiple and ingenious safeguards (akin to the antitoxins described in chapter 3) to minimize the potential collateral damage that would inevitably occur were our own (human) cells to interact with a rogue antibody.
Behring Down on Disease
As we have seen, Robert Koch was a rare character in scientific history. He functioned as a focal point for understanding the body in general and deploying this knowledge to pioneer new medicines. Beyond his own extraordinary insights and personal gravitas, Koch surrounded himself with intellects as impactful as his own, including the ubiquitous Paul Ehrlich. A characteristic that drove Ehrlich to prominence is captured by the modern-day saying “He had a fire in his belly.” Ehrlich was industrious, efficient, and tireless, always exploring new opportunities to glean new insights about health and disease. Fire also rose ceaselessly from his physical being. Despite lifelong repercussions from an early bout with tuberculosis, he smoked cigars constantly and was known to carry a box of cigars with him wherever he went (which might have contributed to the stroke that ultimately claimed him in August 1915).7 Despite the constant plumes of smoke for which he was known, Ehrlich attracted and incubated extraordinary talent, including one colleague who came to Koch’s Berlin Institute in 1888 and whose contributions came as close an anyone else’s to ranking as important as Ehrlich’s or even Koch’s.
Adolf Emil Behring was born on the Ides of March 1854 in the Prussian town of Hansdorf (which was renamed Lawice and now lies in north central Poland).8 As the fifth child (with eleven siblings) of a village school instructor in a sleepy corner of the Prussian state, Emil’s prospects for obtaining an education beyond basic reading, writing, and math were not promising. However, the town minister helped the precocious Emil (he dropped his first name as a child) to gain acceptance at the regional gymnasium in nearby Hohenstein. This Prussian region had a rich tradition of military service, and Hohenstein itself had been the site of many battles since its founding in the 14th century. The many conflicts at this site included the Battle of Grunwald during the Teutonic War, and later attacks by Lithuanian, Teutonic, Swedish, Polish, and Russian invaders, the latter taking part in the Battle of Tannenberg in 1914. This battle took place a half century after Behring’s birth but played a pivotal role in the Eastern Front in which German armies commanded by Generals von Hindenburg and Ludendorff would demolish Russian forces in the early days of the First World War.9, 10 A rich marshal tradition coupled with severe family financial constraints led the young Emil to join the military and seek an advanced degree as a physician at the respected Army Medical College in Berlin. As is still the case in modern-day America, the “free” education came with a price—service in the Prussian military, which Behring began upon graduation in 1878.11
The newly credentialed physician was particularly interested in the nature of infectious diseases, publishing an early scientific paper investigating the antiseptic properties of iodoform, a disinfectant that was just starting to be used as an “antibiotic” to sanitize wounds.12 An antibiotic in the literal sense refers to a compound that kills living things (not necessarily just bacteria). Iodoform was true to this definition and could kill virtually all cells it touched. As such, it wasn’t used only as a disinfectant for wounds; it was also employed for decades as a means, however crude, to kill cancer cells. For example, iodoform was unsuccessfully deployed in 1907 to treat a fateful case of breast cancer in Linz, Austria. Rather than iodoform curing the patient, the patient, Klara Polzl Hitler, succumbed to an agonizing case of iodoform poisoning. This tragedy changed forever the life of her primary caregiver and son, a less beneficent man who shared a first name with Behring.13 (The idea that the horrific experience of being a caregiver to his beloved mother as she was slowly poisoned by iodoform has been speculated as contributing to Hitler’s anti-Semitic views. While Klara’s physician, Eduard Bloch, was indeed Jewish, he had an unusually close relationship with Adolf for the rest of his life. Contrary to the aforementioned theory, Hitler provided Bloch with special protection from the Gestapo until Bloch’s emigration to the United States in 1940.)
The antiseptic properties of iodoform were of great interest to a Prussian military establishment that understood that infectious diseases killed more soldiers than rifles and cannons did. Recognizing the opportunity to improve upon these odds, the Berlin military authorities directed Behring to train with Karl Binz in Bonn. In 1867, Binz had discovered the antimicrobial properties of quinine, a drug that would help limit the effects of malaria.14 British mandarins quickly gained a reputation for seizing upon this new science. Specifically, the Anglo-Indian elites of the Indian Raj embraced the excuse for mixing gin with the quinine-containing tonic (meaning ‘medically useful’) water. Their excuse, albeit defensible, was that the quinine would protect against malaria.
After gaining additional insight on infectious diseases with Binz, Behring was again ordered by the military to move in 1888, this time back to Berlin, where he was to work under Robert Koch.15 Behring remained with Koch until 1895, where he racked up an eno
rmous number of achievements. Koch’s laboratory was arguably the center of advanced biomedical research in infectious diseases at the time, surpassing even the vaunted Pasteur Institute, at least for a while. An interesting insight into how this period affected Behring, both in his personal and professional life, was compiled by the Nobel Foundation (which oversees the eponymous prize). Behring and his wife, Else, had a total of six children, and their godfathers now rank in the pantheon of great biomedical investigators. The godfather of his eldest son, Fritz, was Friedrich Loeffler, who would discover the cause of diphtheria and contributed to the eradication of the disease (as we will soon see). Likewise, the godfather of Hans, his third son, was Friedrich Althoff, who restructured biomedical research within Prussia (and later the greater nation of Germany) to create some of the earliest research institutes and hired the likes of Max Planck, Paul Ehrlich, Robert Koch, and, of course, Emil Behring. Emil Behring, Jr. counted among his godfathers Emile Roux, a cofounder of the Pasteur Institute and a key figure in the development of the medicine that stopped diphtheria in its tracks, and Elias Metchnikoff, who shared the 1908 Nobel Prize in Medicine with Paul Ehrlich “in recognition of their work on immunity.”16
Beyond surrounding himself with influential and successful friends in Koch’s laboratory, Emil Behring himself made extraordinary contributions to medical research. Nor did he work alone. A 34-year-old Emil Behring (these were the years before the honorific “von” had been conferred upon him) began studies in the laboratory of Robert Koch in 1888. By this time, a Japanese scientist, Kitasato Shibasaburo, had already been hard at work with Koch to isolate the agent responsible for tetanus, a bacterium now known as Clostridium tetani. Kitasato succeeded in doing so only months after Behring joined.17 In that same year of 1888, the newly graduated Swiss scientist Alexandre Yersin was transitioning from his doctoral studies at the Ecole Normal Superieure (where he worked with Emile Roux) and spent a few months with Koch, Kitasato, and Behring in Berlin before joining the Pasteur Institute in early 1889. This transient encounter is important to our story, since Yersin’s doctoral work with Roux was spent developing a rabies antiserum and investigators at the Pasteur Institute also had just discovered the toxin responsible for the deadly effects of diphtheria. Thus, the timely visit of Yersin to Berlin clearly resonated with Koch’s team.
The year 1889 would also prove to be a pivotal one for Koch, Behring, and Kitasato. The team formed to begin a series of studies in which sublethal amounts of tetanus toxin were injected into rabbits. The immune system of these rabbits rightly recognized the tetanus toxin as a foreign substance and began to generate antibodies against it, which could be found at high levels in the serum. (Serum refers to a protein-rich substance that remains after whole blood has been subject to coagulation or centrifugation to remove its cellular components.) Behring and Kitasato then tested the sera from these rabbits and found that this material was sufficient to protect other rabbits from the otherwise deadly effects of tetanus.18 The key point here is that the protected animals had not themselves had time to generate their own antibodies (which is known as active immunity) but rather utilized the antibodies found within the serum of previously immunized animals. This process of conferring protection was later known as “passive immunity.” Within days after discovering the concept of passive immunity, Behring’s team was joined by Paul Ehrlich, and the expanded group began to investigate whether they could obtain comparable results with diphtheria toxin.
The Berlin group successfully isolated diphtheria toxin (with guidance provided by Yersin) and used the material to immunize animals. Their goal was to ask if a passive vaccine might be used to treat diphtheria, which remained a major killer of children worldwide. Somewhere along the line (and this is a surprisingly controversial point among a small group of people who become quite passionate about such things), someone began referring to these immune sera as “antitoxins,” since they could counter the effects of a bacterial toxin. By 1890, Kitasato and Behring used this term to describe the substances in sera from immunized animals that could confer protection upon others.19 Since a similar procedure could be used to generate sera that recognized other types of molecules, the serum-based material that conveyed immunity became known by a more generic term: antibodies.
By late 1891, the Berlin team had isolated enough diphtheria antibodies to begin testing in people. The horrible destruction of diphtheria was ever present, and it did not take long to identify potential patients. On Christmas Eve, a very sick eight-year-old boy in a Berlin hospital was successfully treated with the antitoxin and survived an otherwise lethal infection.20 Nine of eleven additional children would be saved over the next few months. The ability to save ten of twelve children contrasted dramatically with the fact that two thirds of untreated children in the same infirmary succumbed to the disease.21
As detailed above, Behring was credited with the discovery of diphtheria antitoxin and would later go on to receive many accolades. In contrast, the contributions of Kitasato and Ehrlich were minimized, especially by Behring himself, who did not credit their work in seminal manuscripts or in his later acceptance of the first ever Nobel Prize for Medicine. Likewise, Behring received a disproportionate amount of credit even though this work was built largely upon foundations established by their French rivals at the Pasteur Institute in Paris. The Berlin team was aware that Emile Roux had been developing a similar antiserum at the same time as Behring, and the Germans might have built upon his experiences. These facts rankled many scientists, who recognize the contributions of their colleagues and appreciate that such work rarely happens in a vacuum or has a single victor.22 Ultimately, some degree of equity was achieved, as Ehrlich would receive a later Nobel Prize for work on immunity, though neither Kitasato nor Roux would ever receive the recognition each scientist rightfully deserved.
Within months, the idea of passive immunization to protect children against diphtheria caught on all around the globe. A key limitation was the availability of antisera. The use of small rabbits as a source of antisera to treat the thousands of children that suffered from diphtheria each year was clearly not viable. With encouragement from the venerable Robert Koch, Behring reached an agreement with Lucius & Bruening of Hoechst Germany (the company was later renamed Hoechst after a merger). Behring then helped scale up production of diphtheria and tetanus antisera using horses rather than rabbits.23
In 1895, Behring left Koch’s team in Berlin and became a professor at Phillips University in Marburg. From a scientific standpoint, his work had peaked with the co-discovery of the diphtheria and tetanus antitoxins.24 His later work at Marburg focused for a time on tuberculosis, and he announced the discovery of a breakthrough for tuberculosis antiserum that might lead to much-needed treatment for that disease. This announcement ultimately proved optimistic, and Behring later abandoned that project due to a lack of sufficient efficacy. Nonetheless, other less scrupulous manufacturers did sell such products, which fed upon an irrational exuberance for antisera in the early years of the 20th century. (The unregulated nature of this new industry is a subject to which we will soon return.)
In 1901, Behring received the inaugural Nobel Prize in Medicine (which coincided with the honorific “von” being added to his name thereafter) and invested his prize monies into a very different venture. In 1904, Behring founded the Behringwerke, a company focused on producing vaccines and antisera for a variety of infectious diseases (including the failed tuberculosis antisera).25 The company continued to operate independently before being subsumed into the larger Hoechst (the company Behring had worked with to commercialize the first diphtheria antitoxins) in 1953. Although it has been subject to a variety of corporate mergers and spin-outs, the company still exists in the form of CSL Behring, a multibillion-dollar, multinational company with facilities in Behring’s native Marburg. Fittingly, however, given the Prussian ancestry of its founder, its international headquarters has since been relocated to King of Prussia—a town in suburban Pennsylva
nia—rather than central Europe.
In an unexpected twist, Behring’s name would again be indirectly linked with research into infectious diseases a half century after his death. In early August 1967, a handful of researchers developing a new poliovirus vaccine at the Behringwerke facility in Marburg reported feeling weak and lethargic, with accompanying headaches and fever.26 These employees were sent home and no great concern was expressed, even after they reported back to the company physician with severe gastrointestinal distress. When the symptoms did not abate by the end of the week, the sickened workers were admitted to the local hospital under the assumption they were suffering from dysentery or perhaps even typhoid fever. Diagnostic tests failed to detect the microbes known to cause these diseases, but they did reveal that the livers of these patients were being systematically destroyed. Soon thereafter, some of the patients began to hemorrhage blood, and roughly a week after their first symptoms were felt, the first patients began to die. Worse still, the infection was not restricted to Marburg. Reports of the same constellation of symptoms arose from Frankfurt and Belgrade. In total, thirty-two people became infected, and seven died.
Within days, the medical and scientific establishments realized this was a new disease with no known etiology.27 Various bacterial and viral causes of the disease were ruled out. As the blood from the infected patients could cause disease in guinea pigs, it was clear this was a new infectious disease. However, the responsible agent could not be seen by either conventional or highly sophisticated microscopes, and the disease arose before the routine isolation and sequencing of DNA that assists disease detectives today. Experts from around Germany and the world were called in to assist in the investigation. Eventually, an experimental electron microscopic technique developed by Dr. Dietrich Peters and Gerhard Muller revealed a strange, twisted viral structure unlike anything ever seen by man.
Between Hope and Fear Page 21
