Don Mason obituary

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.