New concepts about graft-versus-host and graft-versus-leukaemia-reactions. A summary of the 5th International Symposium held in Munich, 21 and 22 March 2002.

The Fifth International Symposium on Graft-versus-Host and Graft-versus-Leukemia Reactions was held on 21 and 22 March 2002 in the University Hospital (Klinikum Grosshadern) of the University of Munich. As in previous years, it was dedicated to the encounter of scientists and clinicians involved in hematopoietic cell transplantation. This year's symposium focused on the characterization of stem cells potentially expanding the use of hematopoietic stem cells and on gene therapy. The immunology section dealt with mechanisms of tolerance, and the characterization of minor histocompatibility antigens presented by major histocompatibility molecules. Further important topics were cytokines and dendritic cells. In 1 and 1/2 days of intense work, the invited speakers, chairmen, authors and an active audience experienced an exciting exchange of ideas and collaboration. Again, new impulses were given for basic research and clinical transplantation. The authors would like to express their deep appreciation and thanks to all participants of this symposium.