Paternal bone marrow infusion as salvage therapy for severe GVHD following maternal haploidentical transplantation resulting in biparental chimerism.

We describe a case of severe GVHD in a 3-year-old child who had received a maternal haploidentical allograft for thalassemia major, which was refractory to several lines of therapy, including weekly infusion of mesenchymal cells. The child was infused paternal marrow graft from which T cells were depleted using Campath 'in the bag' without conditioning. There was significant improvement in gut and liver GVHD over the next few weeks along with persistent mixed biparental chimerism before the child succumbed to CMV pneumonitis. This approach hints at the possibility of using parental TCD marrow to salvage GVHD caused by a graft from the other parent, and raises the possibility of biparental grafting along the same lines as double cord transplantation.