An allogeneic hematopoietic stem cell transplantation that triggers graft-vs.-host-disease (GVHD) involves T cells that do not come from the patient's bloodstream, but rather from the local progenitor cells of the donor tissue. A study from the University of Pittsburgh confirmed this finding after cloning and following these cells, revealing their origin and peculiarities.

“I have had this idea for a pretty long time. In the tissues there are antigen-presenting cells and there are T cells. And I felt like there is no reason why they are needed to be input from blood that it could be a largely local response. Then, the question was whether there would be a subset of cells in the tissues that could continue to sustain it,” lead author Warren Shlomchik told BioWorld.