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

We have designed and evaluated the performance of a simple, rapid, and affordable method for counting CD4⁺ T-cells with the use of plastic microchips. This new system is an adaptation of a "nolyse, no-wash," volumetric single platform assay, and absolute CD4⁺ counts are determined with the use of a microscopic scanning cell counter. To assess the CD4⁺ count test precision and linearity of the system, measured CD4⁺ counts were compared with two other reference assays (single and dual platform flow cytometry) with the use of 123 clinical samples including samples obtained from 35 HIV-infected patients, and artificially diluted samples. A correlation between the results from the use of the new method and from the use of the two other reference assays was r = 0.98 for the clinical samples. A dilution test of the new method demonstrated a linearity of r ≥ 0.99, with coefficients of variation ≤7.6% for all concentration levels. Our findings suggest that the new CD4⁺ counting device can be potentially be applied for other diagnostic procedures that measure quantities of characteristic antigens or other materials on cells.