Special Coverage of 43rd IDSA Meeting: Older HIV patients have higher rates of cell loss, more chronic illnesses
Special Coverage of 43rd IDSA Meeting
Older HIV patients have higher rates of cell loss, more chronic illnesses
HIV patients under age 40 appear to have fewer non-HIV-related chronic illnesses and have better natural killer (NK) immune cells than HIV patients over age 50, new research suggests.
"Younger HIV patients also have higher CD4 cell counts," says Joseph McGowan, MD, medical director of the Center for AIDS Research and Treatment at North Shore University Hospital in Manhasset, NY, and an associate professor of medicine at the New York University School of Medicine in New York, NY.
When compared with older HIV patients, younger ones tend to build up the NK cells better, and they have higher amounts of naïve cells, McGowan says.
Also, immune function is higher in young versus old HIV-positive patients after effective antiretroviral treatment, the study shows.1
"The main purpose of the study was to look at older people with HIV because they’re beginning to represent a larger proportion of people living with HIV," McGowan says. "Effective therapy is allowing people to age normally and to live longer, and people are becoming infected after the age of 50."
With the baby boomer population aging, there will be increased transmission as people maintain their sexual activity, partly due to the use of drugs, such as Viagra, McGowan says.
"Persons presented with HIV over age 50 tend to progress to AIDS or death more quickly than younger people," McGowan says. "Some contribution comes from comorbid conditions."
The study found that at a two-year follow-up, both younger and older HIV patients had no difference in CD4 counts.1
Older HIV patients also tend to be on multiple medications in addition to their antiretrovirals, including drugs to treat cholesterol, diabetes, hypertension, and others, McGowan says.
One of the questions researchers would like to answer is whether the older immune system has the resiliency to regenerate and reconstitute following antiretroviral therapy, McGowan says.
"Or does it take longer, or maybe they do not fully reconstitute because older people don’t have a thymus, which is one of the organs necessary for maturation," McGowan says.
"The thymus experiences involution as people get older," McGowan says. "The thymus is no longer as necessary."
This raises the question of whether there are other parts of the body where lymphocytes could mature later in life, McGowan notes.
"So this study was meant to look at patients who successfully suppressed virus on antiretroviral therapy," McGowan says. "And we assessed how well it does rebuild and reconstitute in a younger group of HIV positives and an older group over age 50 of HIV positives."
The last thing the study looked at was cell death, with the expectation of finding a decrease in cell death when patients were on treatment, McGowan says.
"Basically, that was what was found in these patients," he says.
"The older HIV positive patients tended to have higher rates of cell loss, more apoptosis," McGowan says.
"It may also be a reason why the immune system is not recovering as quickly in older HIV patients," McGowan explains. "The more apoptotic, losing cell lymphocytes at a higher rate, and the body has to generate more lymphocytes to overcome that."
In older patients there might be less regenerative capacity because the cells can only copy themselves so many times, he adds.
Other findings included the better NK cells among younger HIV patients and the higher number of naïve cells among younger patients, McGowan says.
As cancer studies have shown, memory cells are the ones that seem to build up more readily because those are an expansion of cells already in the body, McGowan says.
"What we need is to take this research further," McGowan says.
Clinicians need to keep in mind when treating older HIV patients that it might take longer for immune reconstitution, and there may be a reluctance to hit hard when it comes to HIV, McGowan says.
"But these patients do need to get the virus suppressed, and it’s good to know that their cells do recover, but maybe not with as quick a recovery as in younger persons," McGowan says. "Also, some regimens may be better at suppressing and allowing immune reconstitution than others."
Clinicians should consider the implications of this happening, and they should also keep in mind that previous studies have shown that older patients tolerate therapy well and are at least as adherent as younger HIV patients, McGowan adds.
The study’s investigators would like to look at more patients and start comparing the nature of naïve and memory cells to see if they’re specific to certain antigens, McGowan says.
"We’d like to see if those rates of apoptosis change over time and see lymphocyte tracking studies, which we see as more important," McGowan says. "And as far as viral replication, we want to see which ones will be more vulnerable to that."
As researchers continue to study the impact of HIV infection on older adults, the take-home message for clinicians is to be aware that older persons are at risk for HIV infection, and they should be offered testing and have their risk behaviors reviewed, McGowan advises.
"Education about HIV prevention should be a routine part of the primary care for older people," McGowan says. "Then we have to be aware of any special considerations as the immune system ages."
Reference:
- Small CB, et al. Update on immune function in old & young HIV+ subjects after effective antiretroviral therapy. Presented at the 43rd Annual Meeting of the Infectious Diseases Society of America, Oct. 6-9, 2005, in San Francisco. Abstract: 166.
Subscribe Now for Access
You have reached your article limit for the month. We hope you found our articles both enjoyable and insightful. For information on new subscriptions, product trials, alternative billing arrangements or group and site discounts please call 800-688-2421. We look forward to having you as a long-term member of the Relias Media community.