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Counting White Blood Cells with a Portable Flow Cytometry Device

Posted Apr 11 2013 12:00am

I closely track the development of devices that will enable lab testing in a mini-lab or even a home setting previously that is now only available in hospitals or physician offices. I do this for two reasons: (1) I believe that patients and healthcare consumers should assume more responsibility for their own health; and (2) healthcare providers need to move the locus of much of their delivery to alternative care sites in order to provide cheaper, faster, and better care (see: The Future of Healthcare: Virtual Physician Visits & Bedless Hospitals ). Hence, a recent article about an experimental devices for counting white blood cells caught my eye (see: Counting white blood cells at home ). Below is an excerpt from it:

White blood cells, or leukocytes, are the immune system's warriors. So when an infection or disease attacks the body, the system typically responds by sending more white blood cells into the fray. This means that checking the number of these cells is a relatively easy way to detect and monitor such conditions. Currently, most white blood cell counts are performed with large-scale equipment in central clinical laboratories. If a physician collects blood samples from a patient in the office -- usually requiring a full vial of blood for each test -- it can take days to get the results. But now engineers at the California Institute of Technology..., working with a collaborator from the Jerusalem-based company LeukoDx , have developed a portable device to count white blood cells that needs less than a pinprick's worth of blood and takes just minutes to run.....The prototype device is able to count all five subtypes of white blood cells within a sample. It provides an accurate differential of the four major subtypes....The entire new system fits in a small suitcase...and could easily be made into a handheld device, the engineers say....[The device] detection assay...uses three dyes to stain white blood cells so that they emit light, or fluoresce, brightly in response to laser light. Blood samples are treated with this dye assay before measurement in the new device. The first dye binds strongly to the DNA found in the nucleus of white blood cells, making it simple to distinguish between white blood cells and the red blood cells that surround and outnumber them. The other two dyes help differentiate between the subtypes. The heart of the new device is ...[a] small [channel] to ensure that only one white blood cell at a time can flow through the detection region. The stained blood sample flows through this microfluidic channel to the detection region, where it is illuminated with a laser, causing it to fluoresce.....Thanks to the dye assay, the white blood cell subtypes emit characteristic amounts of red and green light. Therefore, by determining the intensity of the emissions for each detected cell, the device can generate highly accurate differential white blood cell counts.

I understand that only an early prototype is being described above. However, the idea of providing patients with ready access to WBC counts is very interesting. Here's a short quote from the LeukoDx web site: This groundbreaking technology has a wide range of potential applications, from early sepsis detection and monitoring, to HIV/AIDS monitoring and beyond. I am sure that an instrument like this will require some training; hence my reference above to a mini-lab in addition to perhaps home testing. I have always believed that the walk-in clinics that are popping up all over within drug stores or in strip malls should have some basic lab testing capabilities. When this flow-cytometry-based WBC analyzer is ready for prime time, it would be a suitable addition for such facilities.

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