Cite this: Lab Chip, 2013, 13, 2731 CD4 counting technologies for HIV therapy monitoring in resource-poor settings – state-of-the-art and emerging microtechnologies3 Received 15th February 2013, Accepted 22nd April 2013 DOI: 10.1039/c3lc50213a www.rsc.org/loc Macdara T. Glynn, David J. Kinahan and Jens Ducre ´e* Modern advancements in pharmaceuticals have provided individuals who have been infected with the human immunodeficiency virus (HIV) with the possibility of significantly extending their survival rates. When administered sufficiently soon after infection, antiretroviral therapy (ART) allows medical practitioners to control onset of the symptoms of the associated acquired immune deficiency syndrome (AIDS). Active monitoring of the immune system in both HIV patients and individuals who are regarded as ‘‘at-risk’’ is critical in the decision making process for when to start a patient on ART. A reliable and common method for such monitoring is to observe any decline in the number of CD4 expressing T-helper cells in the blood of a patient. However, the technology, expertise, infrastructure and costs to carry out such a diagnostic cannot be handled by medical services in resource-poor regions where HIV is endemic. Addressing this shortfall, commercialized point-of-care (POC) CD4 cell count systems are now available in such regions. A number of newer devices will also soon be on the market, some the result of recent maturing of charity-funded initiatives. Many of the current and imminent devices are enabled by microfluidic solutions, and this review will critically survey and analyze these POC technologies for CD4 counting, both on-market and near-to-market deployment. Additionally, promising technologies under development that may usher in a new generation of devices will be presented. CD4+ T cell counts as an indicator of AIDS Acquired immunodeficiency syndrome (AIDS) was linked to infection with the human immunodeficiency virus (HIV) in the first half of the 1980s, 1–3 and since then over 60 million infections have occurred, leading to over 30 million deaths. 4 Biomedical Diagnostic Institute, National Centre for Sensor Research, School of Physical Sciences, Dublin City University, Dublin, Ireland. E-mail: macdara.glynn@dcu.ie; jens.ducree@dcu.ie 3 Electronic supplementary information (ESI) available. See DOI: 10.1039/ c3lc50213a Macdara Glynn earned his PhD from the National University of Ireland Galway (NUIG) examining DNA damage response pathways of human fibroblasts in response to platinum-based chemotherapeu- tics, and followed this with a postdoctoral fellowship at the Centre for Chromosome Biology where he led projects on epigenetic inheritance mechanisms of the human centromere. Macdara moved to Stokes Bio Ltd. as the Senior Cellular Biologist, where he ran the cell biology facilities and was a member of a multi- disciplinary team designing a massively high-throughput droplet based qPCR system. Macdara is currently a postdoctoral researcher at the Microfluidic Platforms Group at Dublin City University. David Kinahan received his PhD from Stokes Institute, University of Limerick in 2008 for work on fluorescent melting curve analysis of DNA in microchannels. He then joined Stokes Bio Ltd (a spin-out from Stokes Institute that devel- oped high through-put qPCR instrumentation and which in 2010 was acquired by Life Technologies) as a Senior Engineer. The primary focus of his work was instrumentation and firmware development. In late 2010 David was promoted to Engineering Manager; leading a team of 10 engineers which included 4 post-doctoral researchers. In January 2012 David joined the Microfluidic Platforms Group at DCU as a post-doctoral researcher. Macdara Glynn David Kinahan Lab on a Chip CRITICAL REVIEW This journal is ß The Royal Society of Chemistry 2013 Lab Chip, 2013, 13, 2731–2748 | 2731 Published on 22 April 2013. Downloaded by Dublin City University on 29/07/2013 10:07:25. View Article Online View Journal | View Issue