Leo Sachs. 14 October 1924—12 December 2013

Leo Sachs was a worldwide renowned scientist for his major contributions in several fields. In the mid 1950s he showed that amniocentesis could be used for prenatal diagnosis of sex and blood group antigens. He then focused on various aspects of normal development and cancer, including the control of normal haematopoiesis and leukaemia, carcinogenesis in vitro by polyoma and SV40 tumour viruses, chemical carcinogens and X-rays, chromosomes and the reversibility of cancer, surface membrane changes in malignant cells and suppression of malignancy by inducing differentiation. The cell culture system he established in the early 1960s for the clonal development of normal haematopoietic cells made it possible to analyse the molecular basis of normal haematopoiesis, and discover the proteins that regulate viability, proliferation and differentiation of different blood cell lineages and the changes that drive leukaemia. His studies established significant general concepts, including: the differential responsivene...