In most cases, the antigen-experienced B cells do not fight new disease-causing organisms as effectively as do nave B cells, which are responding to an infection for the first time, said John Cambier, Ph.D., co-author of the paper and Chairman of the Integrated Department of Immunology at National Jewish and UCHSC.
B cells secrete antibodies, which bind to and neutralize foreign particles in the body. Antibodies secreted by antigen-experienced B cells were made to fight a previous pathogen and generally do not bind strongly to the current one. Nave B cells can mount a more potent defense because they custom-tailor their antibodies to the current pathogen, allowing the antibodies to bind it strongly.
As occurs in many parts of the aging mind and body, the immune system becomes less responsive to new challenges, said Cambier.
Most immunology researchers have believed that elderly people are less capable of fighting infection because their failing T cells no longer effectively orchestrate the cellular immune response. Although T cells do appear to play a role, Cambier and his colleagues believed there was more to the story.
Their current paper started with a basic paradox. Older mice, and humans, produce fewer and fewer new B cells. Yet, B-cell levels remain high in elderly people and mice. Cambier and his colleagues hypothesized that older mice maintain high B-cell levels by stockpiling antigen-experienced B cells. Exposure to foreign pathogens helps them live longer than naive B cel
Contact: William Allstetter
National Jewish Medical and Research Center