Patients undergoing chemotherapy can experience a reduction in infection-fighting white blood cells, and about 17 percent of the time this results in infectious disease. A device to monitor white blood cell levels at home after chemotherapy would allow these patients to easily detect dangerous declines in white cells and enable immediate treatment with agents that increase white cell production.
Such a prototype instrument has been engineered by an international team of researchers. Designed to be easily used at home, the tabletop device takes a video of blood moving through small capillaries at the base of the fingernail just below the skin. Blue light makes the red cells appear dark and the white cells appear transparent. Because the white cells completely fill the width of the artery as they flow through it, they appear 
A researcher monitors the video showing white blood cells flowing through capillaries located at the base of the fingernail. Source: MIT/The Leuko Projectas a white “gap” in the dark flow of red blood cells moving through the capillary. The gaps can be easily counted and any reduction in the normal number of white cells expected to pass through the capillary can be detected in just one minute.
The group tested the device with 11 patients undergoing chemotherapy treatment. One minute of video was recorded while the user’s finger was placed in the portable tabletop device. The number of white cells that passed through a single capillary were counted to determine whether chemotherapy treatment had reduced the white cell levels to below the threshold where the risk of infection increases. The system proved to be 95 percent accurate in determining whether an individual’s white cell levels were reduced to dangerous levels, and the researchers plan to add automated computer counting to further increase precision.
Scientists from MIT, Universidad Politécnica de Madrid and CIBER-BBN (Spain), Centro Integral en Neurociencias HM CINAC (Spain), Hospital Universitario La Paz (Spain), Massachusetts General Hospital Cancer Center and Harvard Medical School contributed to this research, which is published in Scientific Reports.
