Teruko Ishizaka

Early Life and Background

Teruko "Terry" Ishizaka (石坂 照子, Ishizaka Teruko) was born on 28 September 1926 in Yamagata, in Japan’s Tōhoku region. Contemporary biographical accounts describe her as growing up in a "prominent family", an environment that afforded her educational opportunities unusual for girls of her generation.[1][2] Her birth name was Teruko Matsuura, and she was raised in a period when Japan was undergoing rapid social and political transformation; against this backdrop, her pursuit of medicine represented a significant departure from conventional expectations for women.

Yamagata in the early twentieth century was a relatively rural prefecture, far from Tokyo’s metropolitan universities and research institutes. For a young woman from this area to embark on a career in biomedical science required both academic excellence and considerable determination. Ishizaka’s family support, combined with broader post‑war reforms that slowly expanded access to education, helped enable her entry into medical school at a time when the number of women physicians in Japan remained very small.[1][10]

Education and Training

Ishizaka completed her medical education at Tokyo Women’s Medical School (today Tokyo Women’s Medical University), one of the few institutions dedicated to training women physicians in Japan. She received her doctorate in medicine (M.D.) in 1949, emerging as a fully qualified physician just four years after the end of World War II.[1][3] This period saw substantial reconstruction in Japanese academia and healthcare, and women’s participation in professional fields, though still limited, began to grow.

Driven by a strong interest in basic science and clinical application, Ishizaka pursued further study in immunology. In 1955, she obtained a Ph.D. in medical science from the University of Tokyo, one of the country’s most prestigious universities.[1][3] Earning both an M.D. and Ph.D. placed her within a small elite of women medical researchers in Japan and positioned her to contribute to emerging fields in immunology and allergy research.

Early Career in Japan

Following her doctoral training, Ishizaka embarked on an academic and research career that focused on the mechanisms of immune responses. Early biographical sketches emphasize her work on antibodies and hypersensitivity reactions, although detailed records of her first positions in Japan are limited in the English‑language literature.[1][10] Nonetheless, by the mid‑1950s she was already recognized within Japanese scientific circles as a promising immunologist.

During this time she met Kimishige "Kimi" Ishizaka, an immunologist born in 1925 who shared her interest in allergic disease and antibody biology.[8][11] The two married and formed both a personal and scientific partnership that would last for decades. Their collaboration became emblematic of husband‑and‑wife research teams in twentieth‑century biomedical science, with both contributing intellectually and experimentally to their joint work. Accounts from colleagues consistently refer to them as "the Ishizakas," highlighting the integrated nature of their scientific careers.[6][8]

Migration to the United States and Career Beginnings Abroad

In the late 1950s, Teruko and Kimishige Ishizaka relocated to the United States, joining the post‑war expansion of international scientific exchange. A detailed profile of trend‑setting Japanese women scientists notes that the Ishizaka couple moved to the U.S. in 1957, where they were affiliated with the University of Colorado School of Medicine and later Johns Hopkins University in Baltimore.[10] This move was significant: few Japanese women scientists of her generation obtained long‑term research posts in North America, and even fewer did so in tandem with a spouse.

Their work in the United States centered on the immunology of asthma, allergic rhinitis, and food allergies. By the early 1960s, the Ishizakas were studying so‑called "reagins," mysterious serum factors responsible for causing immediate hypersensitivity reactions but not yet identified as a distinct antibody class.[11][12] Their research placed them at the forefront of allergy science, which at the time struggled to explain why some individuals responded so dramatically to otherwise harmless substances.

In 1962, the couple were recruited to the Children’s Asthma Research Institute and Hospital (CARIH) in Denver, Colorado, an institution focused on pediatric asthma and allergic disease.[1][3][11] This appointment provided a dedicated clinical and research setting for their investigations into hypersensitivity mechanisms. Working with patients and serum samples from highly allergic individuals, the Ishizakas refined immunochemical techniques to characterize the unknown antibodies involved.

Discovery of Immunoglobulin E (IgE)

The culmination of these efforts came in 1966, when Teruko and Kimishige Ishizaka reported the discovery of a new antibody isotype, later designated Immunoglobulin E (IgE).[1][5][10][11][12] At the time, only four major immunoglobulin classes were recognized: IgA, IgD, IgG, and IgM. The Ishizakas’ work demonstrated that the "reagin" activity found in the serum of allergic patients resided in a distinct immunoglobulin class, separate from these known antibodies.[5][11][12]

A key paper, co‑authored by Teruko and Kimishige, unveiled this brand‑new antibody isotype by showing that serum from a ragweed‑sensitive patient contained antibodies to ragweed antigen E that belonged to a previously uncharacterized class.[5] Subsequent studies, many co‑authored by Teruko, confirmed that this antibody was the critical mediator of immediate allergic reactions and that it bound specifically to receptors on mast cells, triggering the release of histamine and other inflammatory mediators.[7][8]

IgE was ultimately recognized as the final major antibody class to be discovered, completing the canonical set of immunoglobulins and reshaping understanding of allergic disease.[12] Its identification provided a molecular explanation for conditions such as asthma, hay fever, and many food allergies, enabling the development of diagnostic tests that measure specific IgE levels and guiding therapeutic strategies aimed at blocking IgE function.

The discovery is widely regarded as a major breakthrough in allergy and immunology. Multiple sources emphasize that Teruko’s contributions were central to the work: she was a full co‑author and co‑investigator, not merely a supporting spouse.[1][5][8] Over their careers, the Ishizakas co‑authored more than 100 papers and reviews on allergy‑related topics, solidifying their status as leaders in the field.[8]

Further Research on Mast Cells and Allergic Mechanisms

After identifying IgE, Teruko Ishizaka continued to explore the cellular pathways through which this antibody exerts its effects. Together with her husband and colleagues, she helped define how IgE binds to high‑affinity receptors on mast cells and basophils, leading to cell activation and mediator release.[7][8] These studies linked molecular immunology with clinical allergy, demonstrating why IgE levels correlate with disease severity and how interventions might target this pathway.

Her later work extended to mast‑cell development. A biographical summary notes that in 1989, Ishizaka published research showing that a human mast cell develops from a haemopoietic stem cell, extending findings previously demonstrated only in mice.[1] This work contributed to the broader understanding of hematopoiesis and the ontogeny of immune effector cells, providing insight into how allergic effector systems arise from bone‑marrow progenitors.

Leadership at the La Jolla Institute for Immunology

In the late 1980s, Teruko and Kimishige Ishizaka took on new roles at the La Jolla Institute for Immunology (LJI) in San Diego, California. A contemporary feature from Asia Research News notes that Teruko became head of the Division of Allergy at LJI, while Kimishige served as the institute’s first scientific director.[8] Another report indicates that the couple joined LJI in 1989, coinciding with the institute’s early growth as a major center for immune‑system research.[7]

At LJI, Teruko’s leadership helped shape an environment focused on the mechanisms of allergic inflammation. Under her direction, the Division of Allergy pursued projects on IgE, mast cells, and related pathways, influencing both basic science and translational efforts aimed at improving allergy treatments.[7][8] Her presence as a senior woman scientist and division head at a leading U.S. immunology institute represented an important example of gender integration at high levels of biomedical research.

Awards, Honors, and Recognition

The significance of Ishizaka’s work on IgE was recognized internationally. For the discovery of the antibody class that mediates allergic reactions, she received a series of major awards:

• Passano Award (1972): In 1972, Ishizaka was awarded the Passano Foundation Award, a prestigious U.S. honor for outstanding contributions to medical science.[1][2] This award acknowledged the transformative impact of IgE discovery on understanding and treating allergic diseases.
• Gairdner Foundation International Award (1973): In 1973, she received the Gairdner International Award, one of the world’s leading biomedical prizes, again for her work on IgE and allergy.[1][2] The Gairdner Award placed her among a global cohort of scientists whose research significantly advanced human health.
• Behring Kitasato Prize (1990): In 1990, Teruko Ishizaka became the first Japanese woman to receive the Behring Kitasato Prize, an honor recognizing outstanding achievements in immunology and infectious disease research.[10][2] This barrier‑breaking distinction underscored both her scientific stature and the gradual opening of major scientific honors to women.

Beyond formal prizes, Ishizaka was widely celebrated within the immunology community. Obituaries and retrospective articles emphasize her reputation for generosity, collaborative spirit, and mentorship toward younger scientists.[9][12] She was remembered not only for scientific insight but also for the collegial atmosphere she helped foster in laboratories and institutes.

Personal Life and Scientific Partnership

Teruko’s marriage to Kimishige Ishizaka was central to her life and career. The couple formed one of the best‑known scientific partnerships in allergy research, frequently co‑authoring papers and jointly shepherding projects from concept to publication.[5][6][8] Collegial tributes refer to them simply as "the Ishizakas," reflecting their near‑inseparable professional identities.[6]

Their collaboration was characterized by mutual respect and shared intellectual leadership. Accounts from colleagues and institutional histories emphasize that Teruko was a full partner in research design, experimental work, and interpretation.[5][8] While some mid‑twentieth‑century narratives of husband‑and‑wife teams tended to highlight the male scientist, more recent profiles seek to correct this imbalance by explicitly recognizing Teruko’s independent scientific contributions and leadership roles.[8][10][12]

The couple had a long life together, working in the United States for more than 35 years and later returning to Japan in retirement.[11][8] Kimishige died in 2018, and Teruko followed in 2019, closing a partnership that had shaped the course of allergy research for over half a century.

Later Life, Retirement, and Death

After decades of service in U.S. institutions such as the University of Colorado, Johns Hopkins, and the La Jolla Institute for Immunology, the Ishizakas retired and moved back to Yamagata, Teruko’s hometown.[8] There, Kimishige served as a specially invited professor at Yamagata University, while Teruko continued to be engaged with the scientific community through writing, mentoring, and occasional lectures.[8]

Her later years coincided with the maturation of many clinical applications derived from the IgE paradigm: allergen‑specific IgE testing became routine in diagnostics, and biologic drugs targeting IgE or its receptor pathways entered clinical practice for severe asthma and chronic urticaria.[7][8][12] Although retired from active bench work, Ishizaka could witness how the fundamental discoveries she had helped make were directly improving patients’ lives.

On 4 June 2019, Teruko Ishizaka died in Yamagata at the age of 92.[1][2][8][9] Major scientific outlets and newspapers marked her passing. The New York Times, for example, reported on her death and highlighted her role in discovering IgE and elucidating the mechanisms of allergic reactions, noting that she "helped transform allergy research."[13] The Scientist similarly described her as a "pioneering immunologist" whose work on IgE and mast cells laid the groundwork for contemporary allergy medicine.[7]

Legacy and Historical Impact

Teruko Ishizaka’s legacy rests above all on her role in the discovery of IgE and the elucidation of its function. By identifying IgE as a distinct antibody class responsible for immediate hypersensitivity, she and her husband provided the molecular key to understanding allergic disease. This discovery:

• Explained why some individuals exhibit extreme reactions to low doses of allergens.
• Enabled the development of serologic tests for allergen‑specific IgE, now standard in clinical allergy practice.
• Guided therapeutic strategies aimed at blocking IgE, its receptor, or downstream mediator release.
• Completed the set of major immunoglobulin classes, refining the conceptual architecture of humoral immunity.[5][7][8][12]

Her work on mast‑cell development further contributed to the understanding of immune‑cell lineages and the origin of effector systems involved in allergy and inflammation.[1] Through both experimental findings and conceptual synthesis, Ishizaka helped embed allergic disease firmly within the broader discipline of immunology rather than treating it as an isolated clinical specialty.

From the perspective of women’s history, Ishizaka stands out as one of Japan’s earliest internationally recognized women immunologists and a rare example of a woman scientist who attained leadership roles in major research institutes in both Japan and the United States. Being the first Japanese woman to receive the Behring Kitasato Prize in 1990 underscored her barrier‑breaking status within the male‑dominated world of high‑profile biomedical awards.[2][10]

Profiles celebrating women in the antibody field routinely list her among the most important contributors to modern immunology.[12] She is frequently mentioned alongside other pathbreaking women scientists as part of efforts to correct historical underrepresentation and ensure that the contributions of women to immunology and allergy research are properly recognized.

Today, IgE is central to virtually every textbook discussion of allergy, and its discovery is taught to medical students worldwide. The routine measurement of specific IgE levels in diagnostic laboratories, the design of anti‑IgE biologic drugs, and the continuing study of mast‑cell activation all trace back to the foundational work of Teruko Ishizaka and her colleagues. As such, her legacy endures both in scientific literature and in the everyday clinical practice that benefits millions of patients with allergic disease.

Assessment within Women’s History

Within the broader narrative of women’s history in science, Teruko Ishizaka’s career illustrates several key themes:

• Educational access and advancement: She leveraged opportunities at Tokyo Women’s Medical School and the University of Tokyo to achieve dual degrees (M.D. and Ph.D.) at a time when very few Japanese women attained such credentials.[1][3][10]
• Transnational scientific mobility: Her move to the United States in the 1950s placed her within leading laboratories and allowed her to participate directly in shaping global immunology.[10]
• Collaborative leadership: As part of a husband‑and‑wife team, she exemplified how women scientists could share intellectual leadership rather than being relegated to subordinate support roles.[5][6][8]
• Institutional influence: Her role as head of the Division of Allergy at the La Jolla Institute for Immunology demonstrated women’s capacity to lead major research units in cutting‑edge biomedical fields.[7][8]
• Recognition and awards: Receiving high‑profile honors such as the Passano, Gairdner, and Behring Kitasato prizes helped challenge implicit biases about women’s suitability for top‑tier scientific recognition.[1][2][10]

For historians of science and medicine, Teruko Ishizaka exemplifies the intersection of gender, nationality, and disciplinary development. Her life story illustrates how a woman from a regional Japanese city could, through education, transnational mobility, and collaborative research, become central to one of the most important biomedical discoveries of the twentieth century. In this sense, her biography is not only a record of scientific achievement but also a lens on the changing structures of opportunity available to women in science.