Flow rate calibration II:: A clinical evaluation study using PanLeucoGating as a single-platform protocol

Background: CD4(+) T-lymphocyte enumeration is vital for monitoring disease progression in individuals positive for the human immunodeficiency virus (HIV), and as a result, there is a need to develop cost-effective protocols that provide accuracy, precision, and affordability. Recently, PanLeucoGating has been shown to fulfill these requirements; however, although comparable to state-of-the-art single-platform protocols (SP), there is still a requirement for an accurate total white cell count. To overcome this limitation, we recently developed a flow-rate based calibration method that enables the PanLeucoGating protocol to be used as a SP approach, and in this study show that this approach can be used for CD4(+) T-lymphocyte enumeration. Methods: A total of 113 HIV samples were analyzed using three protocols: (a) state-of-the art SP bead-based method (MultiSet; predicate protocol), (b) PanLeucoGating protocol used as a dual-platform (DP) approach, and (c) the newly developed flow rate-based SP approach. We demonstrate that flow rate calibration can be achieved easily and that the method is highly comparable to the state-of-the-art SP method. Results: A high correlation was observed between the predicate protocol and the SP PanLeucoGating approach over the whole range of CD4 counts tested (r(2) = 0.9928; bias 8 cells/mul), including the clinically relevant range (e.g., 0-200 CD4 cells/mul; bias 0 cells/mul). For hatched samples, the cost of providing a CD4(+) T-lymphocyte count was reduced to approximately US $1. Conclusions: The SP PanLeucoGating is a cost-effective approach to CD4(+) T-lymphocyte enumeration that maintains accuracy and precision. (C) 2003 Wiley-Liss, Inc.