Determination of CD4+ count:
The sample needed for this test is whole blood collected with EDTA
anticoagulant. The measurement of CD4+ cells is based on the flow
cytometry method. In this method, the blood is first incubated with
specific amounts of antibodies conjugated with fluorescent substances
such as phycoerythrin, the anti-marker to be measured; the cell
suspension is then analyzed in a flow cytometer and the values are
recorded.