The acquisition of a memory phenotype by murine CD4+ T cells is accompanied by a loss in their capacity to increase intracellular calcium.
During the process of aging, the fraction of CD4+ T cells with a naive phenotype, that is, Pgp-1- CD45RBHighMEL-14+, decreases in favor of CD4+ T memory cells. Total CD4+ T cells from aged mice displayed a diminished calcium response to anti-CD3 and even ionomycin as compared to the cells from young mice, and this was related to the changed composition of the CD4+ T-cell population. Regardless the age of the donor mice, naive CD4+ T cells effectively increased intracellular calcium, whereas memory CD4+ T cells were impaired in this regard. In addition, a heterogeneity in the differentiation stage of the naive CD4+ T cells was shown by the observation that calcium mobilization in naive CD4+ T cells from young mice was more profound than that in their aged counterparts. These data thus indicate that during the acquisition of a memory phenotype, murine CD4+ T cells lose the capacity to increase intracellular calcium, which in turn may be responsible for the decreased level of IL-2 production by these cells.
Section of Immunology, TNO Institute of Aging and Vascular Research TNO, Leiden, The Netherlands.
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Hertogh-Huijbregts
D000375:Aging / Q000502:physiology*; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D017252:CD3 Complex / Q000276:immunology / Q000502:physiology; D015496:CD4-Positive T-Lymphocytes / Q000502:physiology*; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology*; D007156:Immunologic Memory / Q000187:drug effects / Q000502:physiology*; D016130:Immunophenotyping; D015759:Ionomycin / Q000494:pharmacology; D017493:Leukocyte Common Antigens / Q000502:physiology; D008297:Male; D051379:Mice; D008808:Mice, Inbred CBA
D000911:Antibodies, Monoclonal; D017252:CD3 Complex; D015759:Ionomycin; D017493:Leukocyte Common Antigens; D002118:Calcium