title: The effect of age on the cognate function of CD4+ T cells.
abstract: With increasing age, the ability to produce protective antibodies in response to immunization declines, resulting in reduced efficacy of vaccination. We have examined how reductions in CD4(+) T-cell function contribute to reduced humoral responses, using a model that allows us to compare identical numbers of antigen-specific naive T cells from young and aged T-cell receptor transgenic mice. Naive cells from aged mice exhibit reduced responses, both in vitro and in vivo. In vitro, responses of aged T cells can be enhanced by addition of interleukin (IL)-2. In vivo, using an adoptive transfer model with young hosts, naive cells from aged mice exhibit significant reductions in cognate helper function, leading to reduced B-cell expansion and differentiation. These age-related defects could be overcome by prior in vitro T helper 2 effector generation with aged T cells. This improvement in cognate function of the aged effectors may be related to the enhancement of CD154 expression, which occurs on aged T cells in the presence of exogenous IL-2. We also found no difference in B-cell expansion and differentiation when young cells were transferred to young or aged hosts. Our results indicate that age-related reductions in humoral responses are mainly due to defects in the cognate helper function of naive CD4(+) T cells from aged individuals.
authors.affiliation: Trudeau Institute, Saranac Lake, NY, USA. lhaynes@trudeauinstitute.org
authors.forename: Laura
authors.initials: L
authors.lastname: Haynes
authors.forename: Sheri M
authors.initials: SM
authors.lastname: Eaton
mesh_terms: D000375:Aging / Q000276:immunology*; D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D023201:CD40 Ligand / Q000276:immunology / Q000378:metabolism; D006801:Humans; D007376:Interleukin-2 / Q000494:pharmacology; D016328:NF-kappa B / Q000378:metabolism
chemical_list: D007376:Interleukin-2; D016328:NF-kappa B; D023201:CD40 Ligand