150 years after the first description of the clinical picture of "white blood" and the introduction of the term "leukemia" by R. Virchow it appears, that the leukemias, and the acute leukemias in particular, serve as an impressive example for the major improvements that have been achieved in the treatment but also in the understand ing of the biology of malignant dis orders. The international symposia "Acute Leukemia" which are held at Munster since 1986 have developed into an interna tional forum to review the current progress and the future perspectives of leukemia research and therapy at a high scientific and clinicallevel. Since the possibility for active participation in these symposia is somewhat restricted we are glad to have the opportunity to extend the information that was presented at the symposium "Acute Leukemias V - Experimental Approaches and Management of Refractory Disease" which was held from February 27 to March 2, 1994 to a broader audience of basic scientists and clinicians. This meeting was especiaIly designed to discuss experimen tal approaches and the management of refractory disease which allows to evaluate new experimental therapies on the basis of preclinical studies."

Since 1987 Acute Leukemias (AL) has regularly reported on the state of the art in the rapidly growing, successful and exciting field of biology and management of these diseases. In this volume large multicenter clinical trials again form the solid basis for the investigation of leukemic cell biology, the detection of biologic subgroups, their differential response to alternative treatment strategies and the further development of therapy. In particular, this volume addresses mechanisms of chromosomal translocations and transcription factors, risk-adapted treatment strategies, differentiation therapy, secondary AL, special aspects in older patients, and adoptive immunotherapy. Besides the antileukemic approaches, supportive treatment with new antimicrobial substances and growth factors is updated. As a forum of worldwide activities in the field of AL this volume contains both exhaustive overviews on major clinical issues and preliminary data and hypotheses not previously published.