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Cattle twins (1945)

Ray Owen was born on a dairy farm in Genesee, Wisconsin in 1915 and his early experience with observing cattle first hand as a child must have prepared his mind for one of the most important observations in immunology. In 1945 he made the seminal observation that dizygotic (non-identical) cattle twins display red-cell chimerism. In other words, they have two sets of red cells, one made from their own stem cells and one from cells that have slipped into their body from their non-identical twin early in the shared foetal life whilst in the same womb.

His discovery came out of the blue and was largely ignored until it was it was later highlighted by Frank Macfarlane Burnet and Frank Fenner in their influential monograph “The Production of Antibodies” in which they predicted the existence of immunological tolerance as a result of “self markers”, which could explain why the body’s immune system does not normally react against “self”.

Then in 1951, Peter Medawar, working initially without knowledge of Owen’s earlier observation, started a set of experiments that conclusively demonstrated how immunological tolerance can be experimentally induced in foetal mice and chick embryos. The research could explain the paradoxical observation that tissue grafts between non-identical twins were accepted. The findings were critical in the development of organ transplantation.

Medawar and Burnet shared the 1960 Nobel Prize for their discovery of acquired immunological tolerance, although Medawar always believed that Owen should have also been named as one of the co-winners of the Nobel for his seminal 1945 observation relating to cattle twins.