Those of us with worn down, ineffective immune systems bloated with uselessly duplicated memory cells - at the expense of naive T cells ready to fight new invaders - can lay a large share of the blame at the door of Cytomegalovirus (CMV):
this appears to be the essential problem of design at the core of the aging immune system - you simply run out of space. Given the large degree to which immune system decay contributes to age-related frailty, suffering and death, it would be a big step forward to find a way to repair this mode of failure.
In recent years, it has become clear that this running out of space is not caused by a wide range of immunological threats - rather one type of virus is largely responsible for the entire problem.
CMV doesn't really hurt you at all in the short term; most people don't even show symptoms. But because you cannot clear it from your system, its presence chews up more and more of your limited immune resources with time.
This is what happens to all of us with increasing age, speeding the downward spiral: if your immune system isn't up to snuff, you're that much less able to resist further damage. Modern medicine is beginning to offer the opportunity to do something about that, however. I noted one approach to fighting CMV a little while ago, and here is more good news:
“Until now, scientists haven’t been able to develop a vaccine to protect against CMV,” said Deborah H. Spector, Ph.D., UCSD Professor of Cellular and Molecular Medicine and faculty member of the Skaggs School of Pharmacy and Pharmaceutical Sciences. “Using a two-pronged approach, we successfully created and tested a vaccine in a mouse model with CMV that shows enormous promise for re-directing the body’s immune system, enabling it to fight the virus.”
The mouse vaccine generates an immune response that protects against both infection and development of disease when the virus is present by completely disarming the virus’s ability to replicate and establish a persistent infection.
“Our approach generates an immune response that is different from the normal response to the virus, and we hope to have found an ‘Achilles’ heel’ in the defenses that the virus uses to evade the immune system,” said Spector. “The virus has evolved to persist in the host by evading the immune responses either by hiding or by misdirecting the host’s immune responses. We found a way to teach the host immune system to not be tricked by the virus.” She added that the next step is to apply this strategy to create a vaccine for use in humans.
Unfortunately, this is unlikely to help those aged folk already possessed of CMV-obsessed immune systems - you'd need something like a reboot of the immune system, or a therapy to target and eliminate specific memory T cells, or the ability to restore your immune system to an earlier version. While even the middle-aged would benefit greatly from eliminating all ongoing effects of CMV, it is good to see that the potential options are expanding for those already damaged. It is in all our interests to see the options for repair improving more rapidly than the options for prevention.