Preservation of immune repertoire by selective depletion of haploidentical grafts

An important barrier to the success of transplanting haploidentical hematopoietic stem cells is delayed reconstitution of immune cells that provide protection from opportunistic infections and recurrent malignancy. In recent years a large research effort has been directed toward improving immune reconstitution through methods that potentially spare these cells while simultaneously reducing the alloreactive lymphocytes that cause graft-vs.-host disease. The basic concepts that support three very different approaches to selective depletion of haploidentical grafts are described in this section. Two methods take advantage of the proliferation of donor T cells after encountering alloantigen, and the third method exploits newer technology to engineer a graft that excludes alloreactive T cells while preserving other immunomodulatory cells.