Leslie Baruch Brent obituary
Leslie Baruch Brent, who has died aged 94, was a PhD student at University College London when he co-authored the first of two groundbreaking papers. In 1953 he showed that immunological tolerance - the capacity to accept an unrelated tissue transplant - could be experimentally induced. This won lifelong fame for him and his two senior colleagues, Peter Medawar, the team leader, and Rupert Billingham, a postdoctoral researcher. They were nicknamed "the Holy Trinity" by American immunologists. We now take for granted that tissues and organs can be transplanted even if the recipient is genetically dissimilar and perpetually takes powerful drugs that suppress the immune response. This was unthinkable in the early 1950s.
In the 40s Medawar had proved that "foreign" tissues are usually rapidly destroyed by the same immune system that also fights infections. Billingham, Brent and Medawar began their landmark experiments inspired by previous observations. The US immunogeneticist Ray Owen had shown in 1945 that dizygotic (fraternal) twin calves have red blood cell chimerism, the red blood cells of each mingling with others originating from their twin while in the womb. Owen postulated that precursor red cells must have been exchanged before birth, that the foreign cells had been accepted, and that they had established their own lineage.
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