Document 1177
 DOCN  M9591177
 TI    The survival and turnover of mature and immature CD8 T cells.
 DT    9509
 AU    McDonagh M; Bell EB; Immunology Research Group, Medical School,
       University of; Manchester, UK.
 SO    Immunology. 1995 Apr;84(4):514-20. Unique Identifier : AIDSLINE
       MED/95309959
 AB    The present investigation has examined the phenotype, survival and fate
       of immature and mature CD8 T cells. CD4- CD8+ 'single positive'
       thymocytes (a model for recent thymic emigrants) were Thy-1+ CD45RC-
       RT6- before transfer to normal euthymic recipients, but changed
       phenotype within 7-10 days to become Thy-1- CD45RC+ RT6(+)--the
       phenotype of mature resting CD8 T cells. Following transfer to athymic
       nude recipients CD8 T cells from thoracic duct lymph of allotype-marked
       rats increased 12-17-fold during the first 2 months. Proliferation
       occurred in the complete absence of CD4 T cells and the donor CD8 T
       cells persisted [at 15-18% of peripheral blood lymphocytes (PBL)] for
       the life of the recipients. When combined with equal numbers of CD4 T
       cells, however, CD8 T cells occupied only 3-4% of PBL; in these animals
       CD4 T cells plateaued at 15-16% of PBL. The results suggested that CD8 T
       cells competed poorly with rapidly dividing CD4 T cells for limited
       space in a recirculating pool in which total T-cell numbers are
       homeostatically regulated. Although able to proliferate and self-renew
       in athymic nude recipients, when transferred to normal euthymic animals
       donor-derived mature CD8 T cells declined in number with time; their
       half-life was estimated to be 34 days. Similar studies with purified
       CD4- CD8+ 'single positive' thymocytes gave a comparable half-life of 37
       days. The results indicated that lifespan was not due to an ageing
       process among CD8 T cells, but was rather a reflection of cell turnover
       dependent on thymic output.
 DE    Animal  Antigens, CD45/ANALYSIS  Cell Communication/IMMUNOLOGY  Cell
       Differentiation/IMMUNOLOGY  Cell Division/IMMUNOLOGY  Cell
       Survival/IMMUNOLOGY  CD4-Positive T-Lymphocytes/IMMUNOLOGY  CD8-Positive
       T-Lymphocytes/*CYTOLOGY/IMMUNOLOGY/TRANSPLANTATION  Immunomagnetic
       Separation  Lymphocyte Transfusion  Rats  Rats, Inbred Strains  Rats,
       Nude  Support, Non-U.S. Gov't  T-Lymphocyte Subsets/IMMUNOLOGY  JOURNAL
       ARTICLE

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