Landmark IL-2 Discovery, 50 Years On, Recognized as Foundation of Modern Cancer Immunotherapy
核心洞察
A new Landmark Perspective in Science marks the 50th anniversary of Robert C. Gallo's 1976 discovery of a human T-cell growth factor later named interleukin-2 (IL-2).
The discovery enabled long-term culture of human T cells (搜索), leading to identification of the first human retroviruses HTLV-1 (搜索) and HTLV-2 (搜索) and establishing human retrovirology.
The same capability proved critical to characterizing HIV (搜索) as the cause of AIDS (搜索) and to developing the HIV blood test, improving global blood supply safety.
A discovery made half a century ago in a laboratory searching for human retroviruses has been formally recognized as one of the pivotal advances that made modern cancer immunotherapy (搜索) possible. A new Landmark Perspective published in Science, timed to the 50th anniversary of Robert C. Gallo's seminal 1976 paper, traces how research aimed at growing human T cells (搜索) in the laboratory led to the identification of interleukin-2 (IL-2) and reshaped immunology, virology and cancer medicine.
The Perspective was written by Rafi Ahmed, PhD, director of the Emory Vaccine Center (搜索) and a leading authority on T-cell immunity and immune memory, and Steven A. Rosenberg, MD, PhD, chief of the Surgery Branch at the National Cancer Institute and a pioneer of cancer immunotherapy (搜索). They conclude that Gallo's discovery was a pivotal advance that made the discovery of IL-2 possible, fundamentally transforming scientists' ability to study the human immune system and laying the foundation for today's most transformative cancer immunotherapies.
"Modern cancer immunotherapy (搜索) became possible because scientists learned how to isolate, grow and understand human T lymphocytes," Rosenberg said. "Few scientific advances have had such far-reaching consequences across both immunology and cancer medicine. Dr. Gallo's work fundamentally changed what became possible."
Solving a Fundamental Problem in T-Cell Biology
At the center of the scientific history was a longstanding challenge Gallo and his colleagues set out to solve: how to grow human T cells (搜索) outside the body over extended periods. Their research identified a naturally occurring factor that stimulated T-cell growth, later named IL-2. The ability to grow T cells in the laboratory opened the way to subsequent advances in cellular immunotherapy, including tumor-infiltrating lymphocyte (TIL) therapy, CAR-T cell therapy and other treatments that harness the immune system to fight cancer.
The work began from a question many scientists at the time doubted was worth pursuing: did human retroviruses exist? Gallo's team studied human blood cells and investigated leukemia (搜索) and lymphoma (搜索), and learning how to keep human T cells (搜索) alive and growing in the laboratory allowed them to find out.
"When my colleagues and I published our findings in Science in 1976, our goal was to solve a fundamental scientific problem that would allow us to determine whether human retroviruses existed," Gallo said. "We could not have predicted how broadly those discoveries would influence immunology, virology and cancer research. Science advances by following evidence, not expectations."
A Tool That Reshaped Retrovirology and HIV Research
The breakthrough also reshaped the course of virology. It enabled Gallo and his colleagues to discover the first human retroviruses, HTLV-1 (搜索) and HTLV-2 (搜索), establishing the field of human retrovirology. Building on those discoveries, Gallo co-discovered that HIV (搜索) is the cause of AIDS (搜索) and led the development of the blood test to detect HIV, dramatically improving the safety of the world's blood supply while advancing scientists' understanding of the human immune system.
"IL-2 fundamentally changed what was possible in human retrovirology," said William W. Hall, MD, PhD, co-founder of the Global Virus Network (搜索) (GVN), director of its Center of Excellence at University College Dublin and professor emeritus at UCD. "For the first time, we could maintain and expand human T cells (搜索) in culture, giving us the ability to isolate and characterize human retroviruses in ways that had not been possible before. Mark Kaplan and I used IL-2-treated lymphocytes to isolate multiple strains of HTLV-2 (搜索)."
Christian Bréchot, MD, PhD, vice chair and president emeritus of GVN and former president of the Institut Pasteur, noted that IL-2 became an essential tool in human retrovirus research, including work in Gallo's laboratory at the National Cancer Institute and at the Institut Pasteur in France that led to the discovery of HIV (搜索) and helped establish it as the cause of AIDS (搜索). "It shows how a discovery made in one laboratory can enable advances across institutions, countries and fields of science," he said.
An Argument for Sustained Basic-Research Investment
The anniversary arrives as governments and research institutions worldwide weigh how much to invest in biomedical science, particularly basic research that may have no obvious application when the work begins. Ahmed framed the discovery as a case study in that value.
"One of the enduring lessons of biomedical science is that the greatest discoveries often have applications far beyond their original purpose," Ahmed said. "Dr. Gallo's work is an outstanding example of how fundamental research can create entirely new scientific opportunities that continue to transform medicine decades later."
Quarraisha Abdool Karim, PhD, a GVN Board member and associate scientific director of CAPRISA (搜索), a GVN Center of Excellence in South Africa, said the findings from five decades ago "highlight what enduring, game-changing scientific breakthroughs look like and why ongoing investments in curiosity research remain critical to advance human health."
Anders Vahlne, MD, PhD, professor emeritus in clinical virology at Karolinska Institutet in Sweden and a member of the GVN Board Executive Committee, added: "The legacy of IL-2 is still being written. Being first to make a fundamental discovery can change the direction of science. IL-2 opened new areas of research, and generations of scientists have taken that discovery in directions no one could have predicted in 1976."
From Tampa Symposium to Venice 2027
The new Science Perspective grew out of a scientific gathering held earlier this year in Tampa. The inaugural Microbes, Genes & Cancer Symposium, hosted by the Tampa General Hospital Cancer Institute (搜索) and USF Health Morsani College of Medicine in partnership with GVN, brought together more than 100 internationally recognized investigators in virology, immunology, oncology and microbial oncogenesis. A special session marking the 50th anniversary included Gallo, Ahmed and Rosenberg.
"Cancer immunotherapy (搜索) represents one of the defining advances in modern oncology, and IL-2 helped open possibilities that scientists continue to build upon today," said Eduardo M. Sotomayor, MD, vice president and executive director of the Tampa General Hospital Cancer Institute (搜索).
The scientific exchange will continue March 11–13, 2027, in Venice, Italy, at the 2nd Microbes, Genes & Cancer Symposium, where scientists from around the world will examine new developments in immunology, cancer biology, microbial oncogenesis and translational medicine. The meeting will be held in partnership with the annual European LeukemiaNet/Kompetenznetz Leukämien Symposium, the Tampa General Hospital Cancer Institute (搜索) and GVN.
Gallo, who serves as founding director of the USF Health Institute for Translational Virology and Innovation (ITVI), James P. Cullison Professor of Medicine at the University of South Florida Morsani College of Medicine, director of the Microbial Oncogenesis Program at the Tampa General Hospital Cancer Institute (搜索) and co-founder and chair of the GVN Scientific Leadership Committee, distilled the anniversary's lesson plainly.
"The obvious research is often about what is not obvious," he said.