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.

Background: HIV monitoring in resource-constrained settings demands affordable and reliable CD4 + T lymphocytes enumeration methods. We developed a simple single platform image cytometer (SP ICM), which is a dedicated volumetric CD4 + T lymphocytes enumeration system that uses immunomagnetic and immunofluorescent technologies. The instrument was designed to be a low-cost, yet reliable and robust one. In this article we test the instrument and the immunochemical procedures used on blood from HIV negative and HIV positive patients.Methods

Background: We developed a volumetric single platform image cytometer (SP ICM) that is dedicated to count CD4 1 and CD8 1 T lymphocytes for HIV monitoring in resource-constrained settings. The instrument was designed to be low-cost, yet reliable, easy-to-use, and robust.Methods: Whole blood is incubated with CD3-magnetic nanoparticles, CD4-phycoerythrin (PE), and CD8-peridinin-chlorophyll-protein complex (PerCP). The CD3 cells are immunomagnetically attracted to an analysis surface, where fluorescence images of CD4 1 and CD8 1 T lymphocytes are recorded and analyzed, respectively. We compared CD4, CD8 counts, and CD4/CD8 ratio obtained by the SP ICM with those from a SP flow cytometer (FCM) tetraCXP method on blood samples from 145 patients.Results: Good correlations were obtained (R: 0.96-0.99) between the SP ICM and the SP FCM. There was 10% CD8 undercount in the SP ICM, which could be partly caused by CD8 1dim T lymphocytes that were not detected by the instrument or not counted by the image analysis due to the cross-talk from the CD4-PE signal in the CD8-PerCP image.Conclusions: The SP ICM is a good candidate for HIV monitoring in point-of-care settings of resourceconstrained countries. q