Simple test to monitor immune status of HIV patients

Joanna Carpenter
23 July 2007
Source: SciDev.Net

Researchers have developed a small, simple and affordable device to monitor HIV-infected patients' immune systems in developing countries. This technology could help doctors more readily assess when a patient needs to begin antiretroviral therapy.

The research was published this month (July) in the Journal of Acquired Immune Deficiency Syndromes.

Lead researcher Bill Rodriguez, from Massachusetts General Hospital and Harvard Medical School in the United States, says that to assess how well an HIV-positive person's immune system is functioning, you need to count a component of the immune system, called CD4+ T-cells. 

HIV targets these cells and so their numbers in the blood are a good indicator of how likely an HIV-infected patient is to become ill, and thus what level of treatment they need.

The current technology doctors use to count CD4+ T-cells is not readily available in the developing world; laser flow-cytometry machines cost US$30,000–150,000 and require skilled health workers to process samples and analyze data.  

The authors write that the microchip device, the size of a business card, will be "cost-effective" and relatively simple to use.

The device contains a tiny chamber that is filled with a finger prick sample of the patient's blood. A special coating on the inner chamber walls catches the CD4+ T-cells so that when the chamber is flushed through they are left behind and can be counted using an ordinary microscope.

Rodriguez and team have plans for testing the device in Brazil, Uganda and Rwanda. "We have partners in all three [countries], but are still working… to get official approval," he says. The next step is to convert the laboratory prototype into a form for mass production.

Peter Mugyenyi, Director of the Joint Clinical Research Centre in Kampala, Uganda, describes the new device as "exciting provided it is affordable."

"Africa will in the near future have millions of people on [antiretroviral therapy]," says Mugyenyi. He says at the moment it is not practical to use existing methods to monitor all patients who might need the therapy, because of the complexity of the technology and problems with power shortages.

But Frances Gotch, a professor of immunology from the United Kingdom's Imperial College in London, says developing countries deserve the same equipment as the developed world. "We need to build up scientific laboratory infrastructure in developing countries," she says.

Reference: Journal of Acquired Immune Deficiency Syndromes 45, 257 (2007)