In Remembrance

Leonard Herzenberg

Leonard Herzenberg, PhD, professor emeritus of genetics at the Stanford University School of Medicine, died October 27 at Stanford Hospital. His wife and longtime collaborator, Leonore (Lee) Herzenberg, and their dog, Gigi, were by his side. He had been hospitalized since he suffered a severe stroke on October 8. He was 81.

Herzenberg was honored with a Kyoto Prize in 2006 for his role in the development of the first fluorescence-activated cell sorter, or FACS. He also was awarded a Special Novartis Prize in Immunology in 2004 for his role in developing fluorescent-labeled antibodies to tag cells prior to FACS sorting.

Herzenberg was well known for his pursuit of social justice, his desire to help those less fortunate then himself and his warm and welcoming demeanor. He donated the money accompanying his Kyoto Prize to nonprofit organizations working to improve health, human rights and education.

Len was a valuable and treasured member of our Stanford Medicine community for more than 50 years, said Lloyd Minor, MD, dean of the medical school. He was a kind, thoughtful and just person eager to share scientific discoveries and opportunities with his friends and colleagues, and to improve access to education and career-advancement opportunities to women and disadvantaged youth. FACS technology made possible the birth of modern immunology, stem cell research and proteomics, and significantly advanced the clinical care of people with diseases such as cancer and HIV infection. Len's scientific accomplishments are prodigious. But it is his commitment to helping others that will be his enduring legacy.

Leonore Herzenberg, also a professor of genetics at Stanford, collaborated scientifically with her husband for more than 50 years. At his insistence, she was formally recognized for her contributions to FACS at the U.S. presentation of the Kyoto Prize.

The couple, who celebrated their 60th wedding anniversary earlier this year, maintained jointly functioning laboratory groups and shared an office remarkable for its colorful décor and low cushions for seating. To colleagues and friends, they were known as Len and Lee—an indomitable duo who were rarely apart, whether hosting department-wide parties at their campus home or discussing their research and planning the next set of experiments.

Without the Herzenbergs, tens of thousands of people now alive would not be, said Irving Weissman, MD, professor of pathology and of developmental biology and the Virginia & D.K. Ludwig Professor for Clinical Investigation in Cancer Research at Stanford. Without Len, the entire conceptual framework of how to evaluate single cells by their 'FACS' signature, and to identify and isolate them from a tissue like bone marrow or a cancer like leukemia, may have never happened. Len and Lee weren't just the central players in the field; for decades they were the field.

They encouraged minority teenagers to pursue a college education by establishing a program to bring high school students from East Palo Alto to Stanford to learn about medicine, biology and the multiple benefits of higher education. In addition, from the 1960s onward, Leonard Herzenberg conducted a behind-the-scenes campaign to expand career advancement opportunities for women in immunology and in science in general.

Changing cell biology

Len was a great man. Not only did he change forever how cell biology is done, he was an inspiring teacher, a deep thinker and a man of high moral conscience, said Nobel laureate David Baltimore, PhD, former president of the California Institute of Technology, who has known Herzenberg for more than 30 years. Baltimore is now a biology professor at CalTech.

Leonard Herzenberg was best known in the scientific arena for developing, in collaboration with his wife, the fluorescence-activated cell-sorter. Like a coin sorter that separates a jumble of change into neat stacks of quarters, nickels, dimes and pennies, the FACS sorts cells according to fluorescent tags attached to their surfaces and keeps the cells viable during the process. Because researchers can couple the fluorescent tags to antibodies that home in on and attach to molecules produced only by certain cell types, the sorter can pluck out rarer-than-rare immune stem cells for further study, or identify stem cells and other populations of cells that are waxing and waning in diseases such as cancer or HIV. The possibilities of the technology, also known as flow cytometry, are limited only by the creativity of the users.

Len was an amazing person in many respects, said Michael Snyder, PhD, professor and chair of genetics at Stanford. Scientifically, he was a giant. The FACS technology was transformative to many fields, and is still regularly used today 30 years after its development. But beyond that, he and Lee have been just fantastically warm and outgoing people who helped make our department feel like a family. There is no question that this is a huge loss.

Tired eyes

The scientific problem in the 1960s that initially set Herzenberg on his path toward the cell sorter was pretty mundane: His eyes hurt. I was sitting in the lab one day counting immunofluorescent cells under the microscope, and I said, 'There's got to be some kind of machine that can do this.' He discovered that scientists at Los Alamos National Laboratory, in New Mexico, had developed a machine to sort cell-sized particles by volume in order to analyze the lung contents of mice and rats exposed to fallout from atomic bomb testing. With characteristic zeal, he headed to New Mexico.

The Los Alamos scientists weren't interested in modifying their system to detect fluorescent and live cells, but after a day and a half they allowed Herzenberg to bring blueprints of their machine back to Stanford. Herzenberg convinced Russ Hulett and William Bonner, two engineers in the laboratory of Genetics Department chair Joshua Lederberg, PhD, to help him modify the Los Alamos plans. Together, they and their colleagues cobbled together the predecessor of the first FACS, dubbed The Whizzer, in the basement of the medical school for about $14,000. They published their success in Science in 1969.

By the early 1970s, the group had incorporated a laser to make the cells fluoresce more brightly, and members of the team invited the inventor of the ink-jet printer, Dick Sweet, to hone the machine's droplet-sorting technique. By 1971, the FACS was up and sorting 5,000 live, functional cells per second, and history had been made.

In the late 1970s, the Herzenbergs spent a sabbatical in the Cambridge laboratory of biochemist Cesar Milstein. There, they learned about hybridoma technology—a means of growing immune cells to produce large quantities of identical, or monoclonal, antibodies for use in research and medicine. Recognizing that pairing monoclonal antibodies with the FACS technology would enable far-reaching diagnostic and therapeutic advances, the Herzenbergs rapidly developed a series of monoclonal antibodies, modeled their use with the FACS, and then widely and freely distributed them to colleagues around the world—sparking the eventual development and use of monoclonal antibodies in the diagnosis and therapy of many human diseases.

Unusual collaboration

The Herzenbergs collaborated with Becton-Dickinson, a medical technology company, to commercialize the FACS technology. In addition, recognizing the importance of monoclonal antibodies to FACS use, they then urged the company to introduce standardized, fluorescently labeled monoclonal antibodies as FACS reagents. This collaboration with industry was unusual because it occurred at a time when most academic scientists were leery of initiating such partnerships. As a result, however, standardized monoclonal reagents soon became widely available to researchers around the world.

Len was a very creative and productive scientist, who also had a remarkable ability to recognize, most often before anyone else did, the potential for practical applications of scientific discovery, said Stanley Cohen, PhD, professor of genetics and the Kwoh-Ting Li Professor in the School of Medicine.

Leonard Herzenberg was born November 5, 1931, in Brooklyn, New York. He attended Brooklyn College, where he met Leonore, and earned a bachelor's degree there in 1952 in biology and chemistry. He then attended graduate school at the California Institute of Technology, where he earned a PhD in 1955 in biochemistry and genetics.

At the time of Herzenberg's graduate studies, the small genetics department at CalTech included seven future Nobel laureates: George Beadle, Max Delbruck, Ed Lewis, Renato Dulbecco, Roger Sperry, James Watson and Barbara McClintock. Two-time Nobel Prize recipient Linus Pauling had a lab nearby. Creative thinking and challenging discussion were the rule; research productivity was the outcome, Herzenberg wrote in a 2004 article in Annual Review in Immunology. Most of the researchers were focused on understanding gene expression and how it affected cellular function in a variety of organisms.

The Herzenbergs became politically active, working with Pauling and others to start a local chapter of the Federation of American Scientists to protest U.S. Sen. Joseph McCarthy's communist witch hunt, which was limiting the academic and personal freedoms of scientists and many other Americans.

A portion of Lee's and my life ever since has been devoted to helping the United States be the kind of country we want our children and children's children to grow up in, Herzenberg wrote in the Annual Review article.

The move to mammalian cells

After completing a postdoctoral fellowship with Nobel laureate Jacques Monod at the Pasteur Institute in Paris, Herzenberg was able to satisfy the requirements of the military draft by taking a position as a public health service officer at the National Institutes of Health—choosing, he remarked, to carry a pipette rather than a gun for my country. There, he learned how to grow mammalian cells in the laboratory of eminent pathologist and mammalian cell biologist Harry Eagle.

Posting to the Eagle laboratory was ideal, since Herzenberg was eager to learn how to conduct genetic studies in mammalian cells. At the time, even growing these cells in culture was an accomplishment, enabled in large part by Eagle's development of a liquid broth of nutrients known as Eagle's minimal essential medium. Herzenberg determined that the addition of pyruvate to the medium allowed the clonal expansion of cells—an important step in his quest to identify drug-resistance markers for use in genetic studies.

When Herzenberg arrived at Stanford in September of 1959, the School of Medicine was undergoing a major transition as it moved from San Francisco to the main university campus. At the time, the buildings were simply standing in a dusty field, and Herzenberg's laboratory space was not yet ready. He set up a workspace in a room in the applied physics building, where his mammalian cell cultures promptly died in an unseasonable California heat wave. (He was able to rescue most of them later from frozen samples.) Lee, who had chosen to be a stay-at-home mom to raise their two young daughters, decided to come in to the lab at least to help Len get settled—an arrangement that Len referred to as "the best decision we ever made." Their enduring partnership in research was thus re-established.

Gadget guy

The Herzenbergs' years at Stanford were marked by extraordinary cross-disciplinary collaborations. In the lab, they brought together biologists with engineers, physicists and software developers, and they began to combine their interests in genetics

Len was a very good inventor, recalled Dale Kaiser, professor emeritus of biochemistry, who knew Len when they were both graduate students at CalTech and who arrived at Stanford at about the same time as the Herzenbergs. He knew quite a bit of physics, and understood how gadgets worked.

In 1961, Lee gave birth to the couple's third child, Michael, who was diagnosed with Down syndrome. As a result, the couple turned their sights on using FACS technology to develop a noninvasive prenatal test for the condition. Diana Bianchi, MD, then a postdoctoral scholar in the lab, took on the project. In 1979, the laboratory published some of the first evidence that fetal lymphocytes can be found circulating in the blood of pregnant women. Bianchi, now the executive director of the Mother Infant Research Institute at Tufts University, continued her efforts and recently collaborated with Stanford biophysicist Stephen Quake, PhD, to show that Down syndrome can be reliably detected from fetal DNA circulating in the blood of pregnant women. This test is now used by hundreds of thousands of women each year and is expected to transform prenatal screening in this country.

In the early 1980s, the Herzenbergs and one of their postdoctoral scholars, Vernon Oi, began collaborating with Columbia University researcher Sherie Morrison, PhD, then on a sabbatical in the laboratory of Stanford biochemist Paul Berg, PhD. Their goal was to create monoclonal chimeric antibodies, each a blend of mouse and human protein sequences, so that the antibodies would be more readily accepted by the human immune system when used for therapy.

Antibody use

The work went well and the Stanford patent on chimeric antibodies was issued in final form in 1998. Today, chimeric antibodies made with this technology are used to treat rheumatoid disease and many other conditions, and the patent stands as the most profitable ever for the university.

Len's influence will continue to be felt for decades in our department and around the world, extending even to people who never met him, said Snyder, the Genetic Department chair, who noted that the Herzenbergs have trained hundreds of scientists through the years.

One of them, Paula Kavathas, PhD, is a professor of laboratory medicine and immunobiology at Yale University. In the 1970s, the message to women scientists was that you couldn't expect to have a family and be successful at a high-powered research university, Kavathas said. But in the Herzenberg laboratory, women were respected and empowered to believe otherwise. This began with the respect that Len showed to Lee.

In the early 1980s, the Herzenbergs became concerned about a mysterious immunological condition that primarily affected gay men. Those affected included friends of members in the Herzenberg laboratories. Strikingly, the FACS and monoclonal antibody technology were central to recognizing that the viral infection resulted in the progressive loss of T lymphocytes, which provide key immune defenses, and the technology became the broadly accepted method for monitoring HIV disease progress.

A source of warmth

One thing I remember the most about Len is his constitutive smiling, said Snyder, using a term from the field of genetics that means constantly on. Len made you feel good—made you want to engage with him and talk with him. He and Lee were a remarkable team and a very, very special couple.

The Herzenberg classroom has populated every corner of the biomedical world, Weissman said. The warm and collegial environment within which sharp critical argumentation could still take place was the model by which their trainees and colleagues have carried out similar arguments in similar homes for decades. What Len brought us by the science he did, and the environment he and Lee created at Stanford, cannot be duplicated; it is what we would have missed if he hadn't been here. It is what indelibly remains after he is gone.

In addition to his wife Leonore, Leonard Herzenberg is survived by four children—Berri, Jana, Michael and Eric (Rick)—and four grandchildren. Continuing in the Herzenberg tradition, Berri established Project Bike Trip to teach bicycle maintenance to educationally disadvantaged high school students. Jana established Motema music, a highly respected jazz and world record label. Rick is a budding potter with interests in the arts.