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Don Mason (1934-2021)

Don Mason, who has died at the age of 86, was a leading immunologist in the UK, making seminal contributions to regulation of immune responses, and particularly to mechanisms of organ transplantation rejection and to theory and concepts of affinity in immune recognition. He trained initially as a physicist (BSc University College, London, 1958)  and for ten years worked on the stability of plasma in controlled thermonuclear fusion, first at ZETA at Harwell, then at Culham. He had a major shift in career after his firstborn son died of leukaemia in childhood.  He returned to University to study medicine (Oxford at  St John’s College). In 1973 he went directly into research at the MRC Cellular Immunology Unit, in the Sir William Dunn School of Pathology, Oxford University, under the direction of Jim Gowans. His ability was recognised immediately and he became a tenured staff member in record time despite a lack of immunology research experience.  He remained there firstly under Gowans, then with Alan Williams and finally as Director himself.  He retired in 1999.  His work, ahead of its time, focussed on centrally important questions establishing new concepts in the field. His physics background was of help when the Cellular Immunology Unit first acquired a Becton-Dickinson FACS-II fluorescence-activated cell sorter in 1974, an approach which subsequently transformed cell immunology.

His immunology career was highlighted by tackling major questions in a rigorous way. For example he showed functional subpopulations of T cells using one of the first monoclonal antibodies – the W3/25 antibody that was later shown to recognise rat CD4. This antibody had been made in a collaboration between César Milstein in Cambridge and Alan Williams in Oxford in 1975. It was one of the first monoclonal antibodies to be used to identify new cell surface proteins and the combination of monoclonals with cell sorting went on to become a standard immunological research approach. Don showed that it was effective in inhibiting a rat autoimmune model for multiple sclerosis. Those early experiments highlighted the potential of immunotherapy with monoclonal antibodies to modify disease, a concept that is now widely used in the clinic. Further analysis of subpopulations showed that the CD4 cells could be split using a CD45 antibody with restricted specificity into two populations of T cells, one that mediated immune responses and the other that actively controlled those responses, now known as regulatory T cells. Don’s work represented some of the foundational studies in the regulatory T cell field, a large and active area of current immunological research. He published classical papers on antibody kinetics and a theoretical paper arguing that the specificity of the T cell receptor had to be broadly cross reactive and not highly specific as was widely argued. This paper has been cited more than 700 times and remarkably after more than 20 years is still cited more than 30 times a year. A testament to the enduring quality of Don’s work that continues to influence immunologists today.

Don ran a small but effective research group training students and post-docs over many years. Many have gone on to be successful immunologists across the world benefiting from the unique training environment Don created. His combination of intellectual rigour with empathy and humility created a positive research culture that was highly influential for his mentees and colleagues alike. He was made an honorary Life Member of the British Society for Immunology in 2017.

He had strong principles and concern for societal issues.  For instance he demonstrated against CRUISE missiles in the 1970’s and against the appalling conditions at Campsfield immigration centre.  Until recently he volunteered as a prison visitor and corresponded with individual prisoners. In retirement he published his personal philosophical monograph: “Science, Mystical Experience and Religious Belief”.   He was a vegan and a Quaker with a very strong family life, living in Witney for many years.  He is survived by his wife Mahalla, their 4 children and 3 grandchildren.

Don Mason, scientist, immunologist, died 13 January 2021 aged 86.

Selected papers

Seddon, B.P., Mason, D. Regulatory T cells in the control of autoimmunity: The essential role of transforming growth factor β and interleukin 4 in the prevention of autoimmune thyroiditis in rats by peripheral CD4+CD45RC- cells and CD4+CD8- thymocytes (1999) Journal of Experimental Medicine, 189 (2), pp. 279-288. Cited 219 times

Mason, D. A very high level of crossreactivity is an essential feature of the T- cell receptor (1998) Immunology Today, 19 (9), pp. 395-404. Cited 702 times.

Saoudi, A., Seddon, B., Fowell, D., Mason, D. The thymus contains a high frequency of cells that prevent autoimmune diabetes on transfer intoprediabetic recipients (1996) Journal of Experimental Medicine, 184 (6), pp. 2393-2398. Cited 112 times

Saoudi, A., Seddon, B., Fowell, D., Mason, D. The thymus contains a high frequency of cells that prevent autoimmune diabetes on transfer intoprediabetic recipients(1996) Journal of Experimental Medicine, 184 (6), pp. 2393-2398. Cited 112 times

Fowell, D., Mason, D. Evidence that the t cell repertoire of normal rats contains cells with the potential to cause diabetes. Characterization of the CD4+ T cell subset that inhibits this autoimmune potential(1993) Journal of Experimental Medicine, 177 (3), pp. 627-636. Cited 422 times

Powrie, F., Mason, D. OX-22high CD4+ T cells induce wasting disease with multiple organ pathology: Prevention by theox-22low subset (1990) Journal of Experimental Medicine, 172 (6), pp. 1701-1708. Cited 336 times.

MacPhee, I.A.M., Antoni, F.A., Mason, D.W. Spontaneous recovery of rats from experimental allergic encephalomyelitis is dependent on regulation of the immune system by endogenous adrenal corticosteroids (1989) Journal of Experimental Medicine, 169 (2), pp. 431-445. Cited 324 times.

Arthur, R.P., Mason, D.T cells that help B cell responses to soluble antigen are distinguishable from those producing interleukin 2 on mitogenic or allogeneic stimulation (1986) Journal of Experimental Medicine, 163 (4), pp. 774-786. Cited 167 times.

Mason, D.W., Charlton, H.M., Jones, A.J., Lavy, C.B.D., Puklavec, M., Simmonds, S.J. The fate of allogeneic and xenogeneic neuronal tissue transplanted into the third ventricle of rodents (1986) Neuroscience, 19 (3), pp. 685-694. Cited 218 times.75)

Mason, D.W., Dallman, M., Barclay, A.N. Graft-versus-host disease induces expression of Ia antigen in rat epidermal cells and gut epithelium (1981) Nature, 293 (5828), pp. 150-151. Cited 203 times.

Mason, D.W., Williams, A.F. The kinetics of antibody binding to membrane antigens in solution and at the cell surface (1980) Biochemical Journal, 187 (1), pp. 1-20. Cited 436 times.

Brideau, R.J., Carter, P.B., McMaster, W.R., Mason, D.W., Williams, A.F. Two subsets of rat T lymphocytes defined with monoclonal antibodies (1980) European Journal of Immunology, 10 (8), pp. 609-615. Cited 614 times.

Webb, M., Mason, D.W., Williams, A.F. Inhibition of mixed lymphocyte response by monoclonal antibody specific for a rat T lymphocyte subset (1979) Nature, 282 (5741), pp. 841-843. Cited 76 times.

White, R.A.H., Mason, D.W., Williams, A.F., Galfre, G., Milstein, C.T-lymphocyte heterogeneity in the rat: Separation of functional subpopulations using a monoclonal antibody (1978) Journal of Experimental Medicine, 148 (3), pp. 664-673. Cited 232 times