Epigenetic CD4+ T-Cell Quantification from Dried Blood Spots Using a Real-Time Quantitative PCR–Based Assay

Despite the clinical importance of CD4 testing for identifying advanced HIV disease, access to conventional flow cytometry remains limited in many settings. Epigenetic real-time quantitative PCR (qPCR)-based immune cell quantification represents a molecular alternative that may be compatible with simplified sample types such as dried blood spot (DBS) specimens. This study evaluated the analytical performance of an epigenetic CD4+ T-cell qPCR assay using DBS samples. Residual EDTA whole blood specimens (N = 150) from patients with HIV were applied to Whatman 903 DBS cards and tested following manual DNA extraction and qPCR using the i.Mune CD4 assay.