My friend and colleague Don Mason, who has died aged 86, will be remembered for his discoveries about cells of the body’s immune system, notably the regulation of lymphocytes, and how fast and with what specificity their receptors recognise parts of foreign molecules.
He began this work in 1973, joining the Medical Research Council’s cellular immunology unit in the Dunn School of Pathology, Oxford University. He stayed for 26 years until his retirement in 1999, by which time he was its director.
Precision separation of cell populations in fluid suspension became possible in the mid-1970s, with Don driving the early adoption in Oxford of fluorescence-activated cell sorting. Combined with the then new monoclonal antibodies against the cell surface, developed by the unit’s second director, Alan Williams, cellular immunology was transformed. With their co-workers, they showed that one of the first monoclonals could turn off CD4 T cells, implying the value of such antibodies for treating disease. Such immunotherapy is now an established drug treatment for many diseases, including cancer.
Don and his colleagues found that CD4 cells comprise two sub-populations, one an initiator and the other a controller of immune responses. This work on regulatory T cells has contributed to a much better understanding of diabetes, and of gut and nervous system autoimmunity.
Don was born in Rochester, Kent, to William, a foreman at the Short Brothers aircraft factory, and his wife, Doris (nee Tew). He attended the Sir Joseph Williamson Mathematical school, then studied physics at University College London. He worked for 10 years on the plasma physics of controlled thermonuclear fusion at Harwell and Culham.
The death of his firstborn son, Donny, of childhood leukaemia pivoted Don’s life towards medicine, which he studied at Oxford (1968-73) before embarking on his immunology research. Strong and principled concern about societal issues permeated his life. Turning vegan in 1977, he discovered the Quakers through CND activism in the 80s while protesting against cruise missiles and the presence of F1-11 nuclear bombers at USAF Upper Heyford, in Oxfordshire.
A week spent in prison for civil disobedience gave him insights that were useful in his later activities as a prison visitor, and for his campaigning on the Campsfield House migrant detention centre near Oxford. In retirement he published Science, Mystical Experience and Religious Belief (2006), topics of enduring interest to him.
He is survived by his wife, Mahalla (nee Thomson), whom he married in 1961, their four children, Jack, Ruth, Jo and Jonathan, and three grandchildren, Amy, Bethany and Milosh.
