George Bellamy Mackaness. 20 August 1922 — 4 March 2007

George Mackaness was an Australian immunologist, educated in Sydney, London and Oxford, who spent his professional career working in Australia and the USA. He is prominently recognized for his work elucidating the life history of the macrophage, the cell in animals so important in combating infection. Mackaness is credited with coining the term ‘activated macrophage’ to denote the enhanced abilities of a macrophage subset that he defined as particularly significant in controlling intracellular infections, of which tuberculosis (TB) is perhaps the most important. In collaboration with students and colleagues over many years, Mackaness built a body of work that better characterized the cellular immune response as complementary to the previously known humoral, or antibody, response and contributed to an understanding of the intercellular communications necessary in initiating and maintaining an effective immune response. In the end, he brought broad attention to the process by which blood monocytes gain increased destructive attributes as a necessary part of the immune response to intracellular infectious agents. Mackaness began his research career during the dawn of antibiotics and contributed importantly to the development of several novel antibiotics for the treatment of TB, among them isoniazid, which is still used to great effect. Less appreciated were his mid-career contributions to heart disease and his later role in bringing the first new class of therapeutics to clinical practice that changed and greatly improved the prevention and treatment of hypertension, stroke, kidney disease, heart attack and congestive heart failure.