T cell immune reconstitution after allogeneic bone marrow transplantation in bare lymphocyte syndrome.
To study the impact of an MHC class II-negative environment on T cell immune reconstitution, we have analyzed the phenotypical and functional characteristics of FACS-sorted cultured CD4(+) and CD8(+) T cells in two Bare Lymphocyte Syndrome (BLS) patients before and after allo-BMT. A similar analysis was performed in two MHC class II expressing pediatric leukemia patients after treatment with an allo-BMT who were included in our study as control. It was observed that CD4(+) T cells displayed cytolytic alloreactivity in both BLS patients prior to and within the first year after allo-BMT, whereas such cells were absent at a later time-point, in the donors and pediatric leukemia controls. In addition, reduced MHC class II expression was observed in CD8(+) T cells of both recipients early after allo-BMT, irrespective of the T cell chimerism pattern. Lack of endogenous MHC class II expression in BLS patients, therefore, results in aberrant T cell selection within the first year after allo-BMT, analogous to T cell selection before transplantation. These T cell selection processes seem to be normalized at a later time point after allo-BMT probably due to migration and integration of graft-derived MHC class II-positive antigen presenting cells to sites of T cell selection.
Godthelp
B C
BC
Departments of Pediatrics, Leiden University Medical Center, Leiden, The Netherlands.
Van Eggermond
M C
MC
Van Tol
M J
MJ
Vossen
J M
JM
van den Elsen
P J
PJ
D000818:Animals; D016026:Bone Marrow Transplantation / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D002455:Cell Division; D019070:Cell Lineage; D020869:Gene Expression Profiling; D006684:HLA-DR Antigens / Q000096:biosynthesis; D006410:Hematopoiesis / Q000276:immunology; D006801:Humans; D016130:Immunophenotyping; D007223:Infant; D016511:Severe Combined Immunodeficiency / Q000276:immunology* / Q000628:therapy; D018183:Transplantation Chimera; D014184:Transplantation, Homologous
D006684:HLA-DR Antigens