Stem Cell Transplant for Immunologic or Histiocytic Disorders

This study tests the clinical outcomes of a preparative regimen of fludarabine (FLU), anti-thymocyte globulin (ATG)/or Campath, and melphalan; followed by hematopoietic stem cell transplant, and a post transplant regimen of Cyclosporin A (CsA) in patients with immunologic or histiocytic disorders. The researchers hypothesize that this regimen will have a positive effect on post transplant engraftment and the incidence of graft-versus-host-disease (GVHD). Patients will be randomized biologically into one of 3 arms based upon donor availability: (a) human leukocyte antigen (HLA) genotypic matched sibling donor, (b) HLA phenotypic matched unrelated peripheral blood stem cell (PBSC) donor, (c) two HLA 0-2 antigen mismatched unrelated cord blood donors (double cord).