Could Lymph Node Removal Slow HIV?
New Finding: Early HIV Infection Centered in Upper Lymph Nodes
Sept. 18, 2003 -- Early HIV infection is centered in just a few upper-body lymph nodes. The finding suggests a radical AIDS therapy: Surgery.
The new discovery is surprising. And it's still unexplained. Two teams of researchers find that the focal points of early HIV infection are the lymph nodes on both sides of the head and neck.
As infection progresses toward AIDS, lymph node infection follows a distinct pattern. The upper lymph nodes burn out. Then the infection moves to the lymph nodes around the lung. As these, too, burn out, the infection finally spreads to the lymph nodes around the bowel.
"Unexpectedly, HIV progression was evident by distinct anatomical correlates, suggesting that lymphoid tissues are engaged [by the virus] in a predictable sequence," write C. David Pauza, PhD, and colleagues at the University of Maryland's Institute of Human Virology in the Sept. 20 issue of The Lancet.
Johns Hopkins researchers David H. Schwartz, MD, and colleagues report similar findings in the same issue of The Lancet.
"The generally superficial location of these nodes makes them surgically accessible," the researchers note.
They suggest that surgical removal be studied. Surgery would, of course, never get rid of all the HIV in the body. The virus would eventually reactivate. But the process might buy precious time, perhaps sparing patients from additional years of dealing with the harsh side effects and cost of anti-HIV drugs.
Monkeys Offer a Clue
The startling findings come from monkey studies Pauza and colleagues performed a few years ago. They infected rhesus macaques with the monkey version of the AIDS virus. At various stages of infection they used whole-body PET scans to analyze lymph node activity. To their surprise, monkey lymph nodes followed a pattern of activation as disease progressed.
Pauza then gave PET scans to 15 patients at various stages of HIV infection. He saw the same pattern in people that he saw in monkeys.
Schwartz's team used the same approach -- only they looked at 12 recently infected patients, 11 patients with long-term infection, and eight uninfected patients -- serving as controls -- whose immune systems were stimulated with flu vaccine.
Interestingly, people with chronic HIV infection who did not progress toward AIDS had only a few active lymph nodes. These tended to be in parts of the body accessible to surgery.
Of course, nobody knows whether surgical removal -- or irradiation -- of the lymph nodes would help or hurt patients. Pauza is a bit skeptical. In a Newsmaker Interview with WebMD's Medscape, he suggests that the best candidates for surgery would be those who are recently infected. Such patients are hard to find, as they don't yet test positive on the most commonly used HIV tests.
"Ultimately, we are interested in using a physical or direct intervention to block the spread of infection," Pauza says. "You can make an argument for radiological or surgical treatment of involved nodes. The acute infection stage would be the best target, but it's difficult to identify patients at that stage and hence to do studies. Once the infection has reached the intermediate stages, the pattern of involvement is really too diffuse."