The open access journal Immunity and Ageing has a pair of review and commentary papers on the front page at the moment. Take a look:
Aging is associated with a decline in immune function (immunosenescence), a situation known to correlate with increased incidence of cancer, infections and degenerative diseases. Innate, cellular and humoral immunity all exhibit increased deterioration with age. ... Circulating melatonin decreases with age and in recent years much interest has been focussed on its immunomodulatory effect.
The problems associated with the ageing immune system and vaccination were discussed recently at an international workshop at the Jenner Institute for Vaccine Research, Compton, UK, 6-7 October, 2005. This is a commentary on that session. The meeting included discussions on T and B cell differentiation and ageing, as well as dendritic cell and neutrophil data, with the emphasis on T cell immunosenescence, perceived as the most important hindrance to satisfactory responses to vaccines in the elderly. The main questions to be addressed in this context are the reasons for dysfunctionality of T cells in the elderly and what to do to improve T cell function.
A lot of things go south when the immune system starts to fail under the burden of accumulated age-related damage. Over the long term, we can hope that present work on a range of immune therapies and stem cell medicine provides a far greater understanding of the immune system - leading to the ability to repair or prevent age-related damage. If you want to extend the life span of a complex machine, you certainly have to extend the life span of the components.