CD4 and CD8 Enumeration for HIV Monitoring in Resource-Constrained Settings

Background: We developed a volumetric single platform image cytometer (SP ICM) that is dedicated to count CD4(+) and CD8(+) 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(+) and CD8(+) 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 similar to 10% CD8 undercount in the SP ICM, which could be partly caused by CD8(+dim) 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 resource-constrained countries. (C) 2008 Clinical Cytometry Society