A single platform image cytometer for resource‐poor settings to monitor disease progression in HIV infection

Abstract

Background For resource‐poor countries, affordable methods are required for enumeration of CD4+ T lymphocytes of HIV‐positive patients. For infants, additional determination of CD4/CD8 ratio is needed. Methods We determine the CD4+ and CD8+ T lymphocytes as the CD3+CD4+ and CD3+CD8+ population of blood cells. Target cells are CD3‐immunomagnetically separated from the whole blood, and CD4‐Phycoerythrin and CD8‐PerCP immunofluorescently labeled. A point‐of‐care single platform image cytometer was developed to enumerate the target CD3+CD4+ and CD3+CD8+ populations. It has light‐emitting diodes illumination, is fully computer‐controlled, operates from a 12 V battery, and was designed to be cheap and easy‐to‐handle. Target cells are imaged on a CCD camera and enumerated by an image analysis algorithm. The cytometer outputs the absolute number of CD4+ and CD8+ T lymphocytes/μl and CD4/CD8 ratio. Results The quality of the cell images obtained with the cytometer is sufficient for a reliable enumeration of target cells. The image cytometer achieves an accuracy of better than 10% in the range of 50–1700 cells/μl. Analysis of blood samples from HIV patients yields a good agreement with the TruCount method for CD4 and CD8 count and CD4/CD8 ratio. Conclusions The image cytometer is affordable (component costs $3,000), compact (25 × 25 × 20 cm3), and uses disposable test materials, making it a good candidate to monitor progression of immunodeficiency disease in resource‐poor settings. © 2007 International Society for Analytical Cytology.

Absolute CD4+ cell count using a plastic microchip and a microscopic cell counter

“…Emergence of these kinds of systems was expected as an alternative cytometric paradigm (22). Among these new systems, volumetric capillary cytometry is an example (23,24), and the use of imaging instruments for CD4 T cells have been reported (10)(11)(12)(13)(14). These systems have adapted similar principles for CD4 counting as compared to our new system.…”

“…However, CD4 counting by flow cytometry is mostly unavailable in developing countries because of the complexity of the method and an associated high cost, whereas manual methods are extremely labor intensive, have a low throughput and are less accurate than the use of traditional flow cytometry methods (5)(6)(7)(8). Therefore, efforts have been made to develop alternative and affordable CD4 1 T cell counting methods for resource-poor settings (9)(10)(11)(12)(13)(14). These recently introduced CD4…”

High-Precision Pinpointing of Luminescent Targets in Encoder-Assisted Scanning Microscopy Allowing High-Speed Quantitative Analysis

“…Quantitative luminescence measurements of biomolecules, single cells and tissue specimens in solid phase are particularly valuable for identification and unambiguous confirmation of rare cell types [1][2][3] , time-lapse study of live cells [4][5][6] , profiling of subcellular components and biomolecular expressions [7][8][9] , and a broad range of other diagnostics applications [10][11][12] . The existing techniques based on digital microscopy [13][14][15][16] , however, are time-consuming and resource-demanding, as images are typically captured for the entire sample area, or even through three-dimensional space [17][18][19][20] , followed by stitching and processing to identify and quantitate targets of interest.…”

Centrifugo-Magnetophoretic Purification of CD4+ Cells from Whole Blood Toward Future HIV/AIDS Point-of-Care Applications

“…Many of these devices have made use of paramagnetic beads to bind cells in a mobile phase and subsequently relocate them to detectors or areas on a chip where they can be manually enumerated. [10][11][12][13] Often, the passage of sample in these devices has been driven by capillary flow. In the work presented here, we build on previous work carried out in this group in which the LOC strategy is integrated into a spinning platform, allowing rapid movement of sample through microfluidic structures and an increase in throughput by placing a number of such structures on a single, DVD-sized disc.…”