Both normal memory counts and decreased naive cells favor intrinsic defect over early senescence of Down syndrome T lymphocytes.
Because of their increased malignancies, autoimmune diseases, and infections, patients with Down syndrome (DS) show features of immunodeficiency. The DS thymus and T lymphocyte subsets have indeed proven to be different, and this has been interpreted as precocious aging. Our study on T lymphocyte subpopulations in DS shows that the normal expansion of naive helper (CD4CD45RA) and cytotoxic (CD8CD45RACD27) T lymphocytes is lacking in the first years of life; this is more logically explainable with an intrinsic T lymphocyte defect. Furthermore, memory cell numbers are not different from age-matched controls (AMC), which does not support the hypothesis of precocious aging. Although the absolute numbers of T lymphocyte subpopulations approach AMC levels toward adulthood, the persistent clinical problems suggest that these cells may not function optimally. However, the clinical picture does not fit severe T lymphocyte deficiency. The latter concept is also supported by our finding that cytomegalovirus (CMV)-seropositive DS children show similar numbers of terminally differentiated cytotoxic T lymphocytes when compared with healthy children, not increased numbers as are seen in immunocompromised hosts.
Kusters
Maaike A A
MA
Departments of Pediatrics, Jeroen Bosch Hospital, 's-Hertogenbosch, 5200 ME, The Netherlands.
Gemen
Eugenie F A
EF
Verstegen
Ruud H J
RH
Wever
Peter C
PC
DE Vries
Esther
E
D000293:Adolescent; D000914:Antibodies, Viral / Q000097:blood; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000821:virology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology* / Q000821:virology; D016922:Cellular Senescence; D002648:Child; D002675:Child, Preschool; D003587:Cytomegalovirus / Q000276:immunology; D004314:Down Syndrome / Q000276:immunology*; D005260:Female; D006801:Humans; D007153:Immunologic Deficiency Syndromes / Q000276:immunology*; D007156:Immunologic Memory; D016130:Immunophenotyping; D007223:Infant; D018655:Lymphocyte Count; D008297:Male; D012189:Retrospective Studies; D016176:T-Lymphocyte Subsets / Q000276:immunology* / Q000821:virology; D055815:Young Adult
D000914:Antibodies, Viral