🇵🇹 Maria de Sousa

Maria Angela Brito de Sousa was born in Lisbon on 17 October 1939, the daughter of a naval officer. As a young woman she faced a real choice between two callings, a career as a concert pianist or a career in medicine, and chose medicine, though music, poetry, and art remained part of her for the rest of her life. She graduated from the medical school of the University of Lisbon in 1963.

Portugal in that era offered little room for a woman who wanted to do fundamental immunological research, and de Sousa left to build her career abroad. In 1968 she went to Scotland, and in 1972 she completed her doctorate in immunology at the University of Glasgow. It was during this period, around 1971, that she did the work for which she is best known.

Studying the movement of lymphocytes by light microscopy, de Sousa observed that different classes of lymphocyte did not distribute themselves uniformly. T cells, those that mature in the thymus, migrated preferentially to particular microenvironments in the peripheral lymphatic organs, while lymphocytes of bone-marrow origin settled in different ones. She coined the term ecotaxis for this directed homing of immune cells to specific tissue niches.

The idea was ahead of its time. It anticipated what later became a major theme of immunology, the understanding that immune cells are guided to defined locations and that the architecture of lymphoid tissue, the placement of cells within it, is itself essential to how immunity works. The concept of lymphocyte homing and tissue-specific microenvironments is now textbook material; de Sousa was among those who first pointed to it.

In 1975 she moved to New York. She became an adjunct professor at what was then Cornell University Medical College and head of the cell ecology laboratory at Memorial Sloan Kettering Cancer Center, where she continued to study how lymphocytes interact with their surroundings, including later work on the relationship between iron and the immune system.

In 1984 Maria de Sousa returned to Portugal, taking up a professorship of immunology at the Abel Salazar Institute of Biomedical Sciences at the University of Porto. There she did what arguably mattered most for her own country: she built the field. She established a master's programme in immunology and helped create doctoral programmes, most notably the GABBA programme in basic and applied biology, designed to train a new generation of Portuguese scientists to international standards. She did not simply import a curriculum; she sent her students into the best laboratories abroad and expected them to return and raise the level of science at home.

Her decision to come back was itself a statement. She had a secure and prestigious position in New York, at one of the world's leading cancer centres, and she gave it up to teach in a country whose research infrastructure was still thin. She believed that talent should not have to emigrate permanently to do good science, and she spent the rest of her career trying to make that true. The brain drain that she fought was personal to her, because she had lived it.

Her later research turned to iron. With colleagues she explored the links between iron metabolism and the immune system, work that connected to the genetic iron-overload disease hereditary haemochromatosis, common in populations of the Iberian peninsula. It was characteristic of her: she kept asking how the chemistry of the body and the behaviour of immune cells were bound together, and she was as comfortable in clinical questions as in basic cell biology.

She became a central figure in Portuguese science, mentoring researchers who went on to lead laboratories of their own and helping to connect Portuguese biomedical research to the wider world. Beyond the laboratory she was known as a writer and poet, publishing under her own name, and as a forceful public voice for science and for women in science, insisting that a small country had every right and every duty to do research of the first rank. Many of today's leading Portuguese biomedical scientists trace their training, directly or indirectly, to programmes she built.

Maria de Sousa died in Lisbon on 14 April 2020, of COVID-19, at the age of 80, as the pandemic she would have understood so well was beginning. She is remembered both for a specific scientific insight, that immune cells navigate to where they belong, and for a broader achievement: she gave Portugal a serious, self-sustaining tradition of immunology and trained the people who carry it forward. Her legacy is measured not only in papers but in scientists.