Linked Life Data

9720647

Source:http://linkedlifedata.com/resource/pubmed/id/9720647

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2-3
pubmed:dateCreated
1998-12-22
pubmed:abstractText
The aging immune system is characterized by a progressive decline in the responsiveness to exogenous antigens and tumors in combination with a paradoxical increase in autoimmunity. From a clinical viewpoint, deficiencies in antibody responses to exogenous antigens, such as vaccines, have a major impact and may reflect intrinsic B cell defects or altered performance of helper T cells. Here we describe that aging is associated with the emergence of an unusual CD4 T cell subset characterized by the loss of CD28 expression. CD28 is the major costimulatory molecule required to complement signaling through the antigen receptor for complete T cell activation. CD4+ CD28- T cells are long-lived, typically undergo clonal expansion in vivo, and react to autoantigens in vitro. Despite the deficiency of CD28, these unusual T cells remain functionally active and produce high concentrations of interferon-gamma (IFN-gamma) and interleukin-2 (IL-2). The loss of CD28 expression is correlated with a lack of CD40 ligand expression rendering these CD4 T cells incapable of promoting B cell differentiation and immunoglobulin secretion. Aging-related accumulation of CD4+ CD28- T cells should result in an immune compartment skewed towards autoreactive responses and away from the generation of high-affinity B cell responses against exogenous antigens. We propose that the emergence of CD28-deficient CD4 T cells in the elderly can partially explain age-specific aberrations in immune responsiveness.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0047-6374
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
102
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
131-47
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1998
pubmed:articleTitle
Functional properties of CD4+ CD28- T cells in the aging immune system.
pubmed:affiliation
Mayo Clinic, Rochester, MN 55905, USA. weyand.cornelia@mayo.edu
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't