Reconstitution of lymphocyte subpopulations after paediatric bone marrow transplantation.
We prospectively studied the reconstitution of lymphocyte subpopulations in a group of 22 children, who survived disease-free at least 6 months after allogeneic BMT for a haematological malignancy. Absolute counts of total lymphocytes, B lymphocytes, T lymphocytes, and CD4+ helper T lymphocytes reached the 5th percentile (p5) of age-matched reference values within 6 months after BMT in 15, 17, 7 and 2 patients, respectively. In particular, CD4+ helper T lymphocyte reconstitution was very slow. Unexpectedly, CMV reactivation had a profound positive influence upon the number of CD4+ helper T lymphocytes in the children. In five patients, absolute B lymphocyte counts above the 95th percentile were reached from 6 months after BMT onwards, mimicking normal ontogeny. Unlike normal ontogeny, the percentages of helper T lymphocytes expressing the 'naive' CD45RA isoform were low and those expressing the 'memory' CD45RO isoform were high in the first 3 months after BMT, as described before. Thereafter, the CD45RA:CD45RO ratio slowly normalised. Also, CD7 expression was absent on up to 90% of T lymphocytes in the first months after BMT, and on a steadily decreasing percentage thereafter, as recently described in adults. However, the absolute counts of CD45RO+/CD4+ and CD7-/CD4+ helper T lymphocytes did not change significantly. So, we found no evidence of peripheral expansion of previously primed donor-derived 'memory' T lymphocytes during the follow-up period which spanned 1-18 months after BMT. The absolute counts of 'naive' CD45RA+ helper T lymphocytes did not show a faster increase after BMT than in adults, despite the presumed presence of a non-involuted thymus in children. Bone Marrow Transplantation (2000) 25, 267-275.
de Vries
E
E
Dept of Paediatrics, Leiden University Medical Centre, Leiden, The Netherlands.
van Tol
M J
MJ
van den Bergh
R L
RL
Waaijer
J L
JL
ten Dam
M M
MM
Hermans
J
J
Vossen
J M
JM
D000293:Adolescent; D019011:Antigens, CD7 / Q000097:blood; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology; D016026:Bone Marrow Transplantation / Q000009:adverse effects / Q000379:methods*; D018956:CD5 Antigens / Q000097:blood; D019070:Cell Lineage; D002648:Child; D002675:Child, Preschool; D003587:Cytomegalovirus / Q000378:metabolism; D005260:Female; D006086:Graft vs Host Disease; D019337:Hematologic Neoplasms / Q000628:therapy / Q000821:virology; D006801:Humans; D016130:Immunophenotyping; D007223:Infant; D017493:Leukocyte Common Antigens / Q000096:biosynthesis / Q000097:blood; D008137:Longitudinal Studies; D018655:Lymphocyte Count; D016131:Lymphocyte Subsets / Q000166:cytology*; D008297:Male; D011446:Prospective Studies; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology; D014184:Transplantation, Homologous / Q000009:adverse effects; D014777:Virus Diseases
D019011:Antigens, CD7; D018956:CD5 Antigens; D017493:Leukocyte Common Antigens