In Memoriam: Fritz Bach – Transplant Pioneer


Fritz Heinz Bach, a pioneer transplant immunologist and the Lewis Thomas Distinguished Professor of Immunology (Surgery) at Harvard Medical School died suddenly on Sunday, August 14, 2011 at his home at Manchester-by-the-Sea, Massachusetts after a long illness. He was 77 years old.

He was generally regarded as one of the early giants of transplant immunology, a visionary whose contributions changed transplant immunology as we know it. His early observations on cell transformations which occur in in vitro cultures of peripheral blood lymphocytes (PBL) from unrelated individuals, his studies on the relation of these changes to the alloimmune response and histocompatibility antigens, and his early application of the mixed lymphocyte lymphocyte culture (MLC) assay to the selection of compatible tissue and organ donors unleashed a veritable perfect storm of related progress in experimental and clinical transplantation that persists to this day.

Bach was born in Vienna, Austria in 1935. After the infamous Kristallnacht pogrom in November 1938, he and his older brother were sent to safety in England in 1939 via the legendary Kinder Transport organized by the British to rescue over 10,000 predominantly Jewish children that were cared for by British families. After being joined by their parents in England, the Bach family immigrated to Burlington, Vermont in 1949 where Bach attended Burlington Public High School before enrolling in Harvard College as a scholarship student and obtaining a Bachelor's degree in 1955. He went on to Harvard Medical School where he became interested in immunology and genetics and graduated in 1960.

Bach undertook internal residency training at New York University where he came under the influence of Lewis Thomas, whom he always credited as being the inspiration for his scientific career. In 1964, Bach and Hirschorn described experiments involving the culture of peripheral blood lymphocytes from two unrelated individuals in vitro for 7-8 days in which some of the cells underwent large cell transformation and division. They estimated the percent of blast cell transformation and mitosis by microscopic examination of fixed smears. They noted that PBL cultures of individuals in whom the probability of sharing HLA antigens had been determined by skin grafting had the lowest number of large cells and mitoses. Bach and Hirschorn suggested that it might be possible to develop mixed lymphocyte cell cultures (MLC) as a typing test for potential recipients and donors of kidney allografts that could identify the most compatible pairs. Later work by Bach and others showed that lymphocytes generated in MLC cultures were cytotoxic to stimulator cells, thereby connecting in vitro alloreactivity with in vivo graft rejection, i.e. the MLC reflected activation of the immune response and the derivative CML reaction (cell mediated lymphotoxicity) represented its effector arm.

Bach worked at the University of Wisconsin from 1965 through 1979. In 1967, he used the MLC assay to select non-reactive, compatible donors for the first successful matched bone marrow transplants performed for immunodeficiency diseases first by Robert Good in Minnesota and then by Bach in Wisconsin, with both cases subsequently reported together as twin papers in The Lancet. This was a milestone in clinical bone marrow transplantation (BMT) which presaged the widespread successful application of BMT in the treatment of diseases. Bach and his group performed extensive studies utilizing the MLC and the derivative CML reaction to study multiple aspects of allograft effector mechanisms and histocompatibility antigens which eventually led to his being among the first to conceptualize that there were two kinds of HLA antigens—those defined by serological methods and those defined by MLC techniques (later called Class I and Class II respectively). Bach subsequently worked at the University of Minnesota from 1979 through 1992 where he continued and expanded his basic studies on T-cell immunogenetics and cytotoxicity, HLA function and structure and the H-2 locus. While at Minnesota, he developed an interest in xenotransplantation which fostered productive experimental collaborations with J.L. Platt, and A.P. Dulmasso and others that examined numerous aspects of xenotransplant rejection.

In 1992, Bach was recruited by the Department of Surgery of the New England Deaconess Hospital (now part of the merged Beth Israel Deaconess Medical Center) and Harvard Medical School to be the Director of the Sandoz Center for Immunobiology Research. The purpose of the new Sandoz Center was to focus collaborative, multidisciplinary research on xenotransplantation and related research areas. Over the next eleven years, he fostered multiple creative and productive collaborations which examined in depth the immunologic, molecular, coagulation/hematologic and genetic mechanisms involved in the genesis and evolution of events leading to xenograft rejection and destruction. A very important outgrowth of these collaborations was that Bach recognized the importance of genes whose purpose it was to provide protection against stress and disease and the need to study how to take advantage of these cytoprotective and homeostatic systems in order to apply them to the prevention and treatment of clinical diseases and inflammatory states. It is noteworthy that in spite of a strong interest in and commitment to xenograft research for the eventual use of xenografts in human clinical transplantation, Bach urged caution against their premature use because of the possibility of introducing serious infections and other diseases into human beings.

Bach was author/co-author on approximately 800 papers. He was a gifted, dedicated, and charismatic teacher. He trained, mentored, sponsored, and encouraged hosts of postgraduate students, fellows, and junior faculty who later rose to academic positions of great prominence and responsibility. He was editor of Clinical Immunology (with R.A. Good), and editor-in-chief of Xeno. He was also a respected and important member of the Society of Clinical Investigation, the American Association of Immunologists, Tthe Transplantation Society, the American Society of Transplant Surgeons, and a charter member of the International Bone Marrow Transplant Registry. His numerous awards included the Distinguished Scientist Award of the American Red Cross (1983), the Medal of the College de France (1984), the Emilio Trabucchi Foundation Award (1989), and the Medawar Prize of Tthe Transplantation Society (1995).

Fritz Bach was married twice, both marriages ending in divorce. He is survived by his ex-wives, six children, and four grandchildren.

Although Bach was passionately and totally engaged in his scientific endeavors, –he also enjoyed wide-ranging interests in classical music, sailing, tennis, travel, food, spy novels and Sunday news shows. He was a warm, friendly, extroverted bon vivant who enjoyed the good things in life and was fun to be with. He genuinely enjoyed being with and socializing with his many friends. They will miss him dearly.

Anthony P. Monaco, M.D.