BONE-MARROW TRANSPLANTATION IN MAJOR HISTOCOMPATIBILITY COMPLEX CLASS-II DEFICIENCY - A SINGLE-CENTER STUDY OF 19 PATIENTS

Major histocompatibility complex (MHC) class II deficiency (bare lymph ocyte syndrome) is a rare inborn error of the immune system characteri zed by impaired antigen presentation and combined immunodeficiency. It causes severe and unremitting infections leading to progressive liver and lung dysfunctions and death during childhood. As in other combine d immunodeficiency disorders, bone marrow transplantation (BMT) is con sidered the treatment of choice for MHC class II deficiency. We analyz ed the files of 19 patients who have undergone BMT in our center. Of t he 7 patients who underwent HLA-identical BMT, 3 died in the immediate posttransplant period of severe viral infections, whereas the remaini ng 4 were cured, with recovery of normal immune functions. Of the 12 p atients who underwent HLA-haploidentical BMT, 3 were cured, 1 was impr oved by partial engraftment, 7 died of infectious complications due to graft failure or rejection, and 1 is still immunodeficient because of engraftment failure. A favorable outcome in the HLA-nonidentical BMT group was associated with an age of less than 2 years at the time of t ransplantation. All the patients with stable long-term engraftment had persistently low CD4 counts after transplantation (105 to 650/mu L at last follow up), but no clear susceptibility to opportunistic infecti ons despite persisting MHC class II deficiency on thymic epithelium an d other nonhematopoietic cells. We conclude that HLA-identical and -ha ploidentical BMT can cure MHC class II deficiency, although the succes s rate of haploidentical BMT is lower than that in other combined immu nodeficiency syndromes. HLA-haploidentical BMT should preferrably be p erformed in the first 2 years of life, before the acquisition of chron ic virus carriage and sequelae of infections. (C) 1995 by The American Society of Hematology.