Thymus-independent expansion of T lymphocytes in children after allogeneic bone marrow transplantation.
The contribution of the thymus-dependent pathway and thymus-independent pathways for T cell regeneration after BMT in children is still unclear. We analyzed the kinetics of T cell regenerative pathways after allogeneic BMT. The number of CD4+CD45RA+ T cells, a thymus-dependent population, was very low until 3 months after BMT. The numbers of CD28- T cells and CD8+ T cells expressing CD8alpha/alpha homodimer (CD8alpha/alpha+ T cells), a thymus-independent population, increased shortly after BMT, beyond the levels of healthy children in some patients. The numbers of Vgamma9+Vdelta2+ and Valpha24+ T cells, which represent populations of extrathymic development, were less than 200/microl during the 6 months after BMT. There was a significant inverse correlation between the percentages of CD4+CD45RA+ and CD28-T cells at 1 month, and a positive correlation between the percentages of CD28- and CD8alpha/alpha+ T cells at 2 and 3 months after BMT. The mean age at BMT was higher in patients with a high level of CD8alpha/alpha+ T cells than in those without an increase in these cells, suggesting the influence of thymic function on the regenerative pathways. These results suggest that the thymus-independent pathway is the dominant source of T cells even in children shortly after allogeneic BMT.
Honda
K
K
Department of Pediatrics, Faculty of Medicine, Kyushu University, Japan.
Takada
H
H
Nagatoshi
Y
Y
Akazawa
K
K
Ohga
S
S
Ishii
E
E
Okamura
J
J
Hara
T
T
D000208:Acute Disease; D000293:Adolescent; D015415:Biomarkers / Q000097:blood; D016026:Bone Marrow Transplantation; D018106:CD28 Antigens / Q000097:blood; D017252:CD3 Complex / Q000097:blood; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D016827:CD8 Antigens / Q000097:blood; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007564:Japan; D007938:Leukemia / Q000276:immunology / Q000628:therapy; D017493:Leukocyte Common Antigens / Q000097:blood; D008297:Male; D009190:Myelodysplastic Syndromes / Q000276:immunology / Q000628:therapy; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000097:blood; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000097:blood; D012038:Regeneration; D016176:T-Lymphocyte Subsets; D013601:T-Lymphocytes / Q000276:immunology* / Q000502:physiology*; D013950:Thymus Gland / Q000166:cytology / Q000276:immunology*; D013997:Time Factors; D014184:Transplantation, Homologous
D015415:Biomarkers; D018106:CD28 Antigens; D017252:CD3 Complex; D016827:CD8 Antigens; D016693:Receptors, Antigen, T-Cell, alpha-beta; D016692:Receptors, Antigen, T-Cell, gamma-delta; D017493:Leukocyte Common Antigens