| In light of the World Health Organization’s plan to deliver antiretroviral therapy (ART) to 3 million people in the
Developing World by the end of 2005, there is an urgent need for an accurate, low-cost, objective, simple and fast
method for CD4+ T cell enumeration during the monitoring of ART. Currently available flow cytometric methods
are relatively expensive ($5–8/test), generate large volumes of waste fluid, and require significant laboratory
infrastructure. Alternative bead-based microscopic methods, e.g., Cytospheres® (Beckman Coulter) and
Dynabeads (Dynal), are also relatively expensive ($3–8/test), difficult to learn (~1 week of training), limited in
throughput (~10 specimens/day), and are subject to the variability of manual microscope counting. In contrast,
the Guava® EasyCD4™ assay is affordable, easy to perform, generates very little waste, and allows for throughput
of as many as 100 specimens/day. The Guava EasyCD4 assay uses anti-CD3 and -CD4 antibodies, a lysis reagent
(Figure 1), and the Guava PCA system (Figure 2). The Guava PCA incorporates a novel, patented technology,
termed microcapillary cytometry or microcytometry, which allows cell analysis assays to be performed on a
system that is low in cost, compact, easy-to-use and maintain, and which produces very little waste (no sheath
fluid is used). User training requires ~4 hours. To evaluate its utility for CD4+ T cell enumeration, the Guava
EasyCD4 assay was compared to a a method currently accepted by clinical laboratories, the BD MultiTest™ CD4
assay. |
