title: Numerical and functional characteristics of lymphocyte subsets in centenarians.
abstract: The immune system in the aged is a very interesting subject for study. In this study, analysis was extended to extrathymic T cells as well as NK cells and "conventional" T cells (i.e., thymus-derived T cells) in terms of their constitution and function in both healthy and unhealthy centenarians. Middle-aged persons were used as controls. Healthy and unhealthy centenarians showed lower levels in the proportion and absolute number of lymphocytes. The major change in the constitution of lymphocyte subsets was increased levels in the proportion of NK cells (CD56+/CD57+) and extrathymic T cells (CD3+CD57+). Inversely, conventional T cells decreased in proportion and function (i.e., proliferative response to mitogen). Although NK cells increased in centenarians, NK activity by whole lymphocytes and the purified NK fraction decreased. The difference between healthy and unhealthy centenarians was small in all parameters, the only difference being a lower level of expression of CD56 antigens on CD57+ T cells in unhealthy centenarians. These results indicate that there is a major shift in lymphocyte population from conventional T cells to NK cells and extrathymic T cells with aging. Concerning the age-associated increases in CD56+ T and CD57+ T cells, these cells correspond to NK1+ T cells in mice.
authors.affiliation: Department of Immunology, Niigata University School of Medicine, Japan.
authors.forename: C
authors.initials: C
authors.lastname: Miyaji
authors.forename: H
authors.initials: H
authors.lastname: Watanabe
authors.forename: M
authors.initials: M
authors.lastname: Minagawa
authors.forename: H
authors.initials: H
authors.lastname: Toma
authors.forename: T
authors.initials: T
authors.lastname: Kawamura
authors.forename: Y
authors.initials: Y
authors.lastname: Nohara
authors.forename: H
authors.initials: H
authors.lastname: Nozaki
authors.forename: Y
authors.initials: Y
authors.lastname: Sato
authors.forename: T
authors.initials: T
authors.lastname: Abo
mesh_terms: D000368:Aged; D000375:Aging / Q000276:immunology*; D019002:CD56 Antigen / Q000378:metabolism; D018959:CD57 Antigens / Q000378:metabolism; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D002455:Cell Division; D048429:Cell Size; D003601:Cytotoxicity Tests, Immunologic; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007564:Japan; D007694:Killer Cells, Natural / Q000276:immunology; D018655:Lymphocyte Count; D016131:Lymphocyte Subsets / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology
chemical_list: D019002:CD56 Antigen; D018959:CD57 Antigens