Andrea Cossarizza

Understanding why some people establish and maintain effective control of HIV-1 and others do not is a priority in the effort to develop new treatments for HIV/AIDS. Using a whole-genome association strategy, we identified polymorphisms that explain nearly 15% of the variation among individuals in viral load during the asymptomatic set-point period of infection. One of these is found within an endogenous retroviral element and is associated with major histocompatibility allele human leukocyte antigen (HLA)-B*5701, whereas a second is located near the HLA-C gene. An additional analysis of the time to HIV disease progression implicated two genes, one of which encodes an RNA polymerase I subunit. These findings emphasize the importance of studying human genetic variation as a guide to combating infectious agents.

The sensitivity and specificity of three fluorescent probes used for cytofluorimetric analysis of mitochondrial membrane potential (delta psi) were studied in the U937 human cell line. First, the role of plasmamembrane in influencing the binding of the probes to mitochondria has been investigated. The depolarization of plasmamembrane with high doses of extracellular KCl had no immediate effects on the loading of JC-1, DiOC6(3) and rhodamine 123 (R123). However, after a few hours of culture in the presence of KCl, significant changes were observed only in cells stained with DiOC6(3). Second, a comparative study was performed concerning the effects of agents capable of collapsing deltapsi. While adding FCCP to cell cultures resulted in consistent changes in the fluorescence emission of both JC-1 and DiOC6(3) - but not of R123 - only cells stained with JC-1 responded to valinomycin. On the whole, our data indicate that JC-1 is a reliable probe for analyzing delta psi changes with flow cytometry, while the others show a lower sensitivity (R123), or a non-coherent behaviour, due to a high sensitivity to changes in plasmamembrane potential [DiOC6(3)]. These data cast some doubts on those studies that, using fluorescent probes that have a low sensitivity to delta psi, hypothesized that the fall in delta psi is one of the early events, if not one of the main causes, of apoptosis.

These guidelines are a consensus work of a considerable number of members of the immunology and flow cytometry community. They provide the theory and key practical aspects of flow cytometry enabling immunologists to avoid the common errors that often undermine immunological data. Notably, there are comprehensive sections of all major immune cell types with helpful Tables detailing phenotypes in murine and human cells. The latest flow cytometry techniques and applications are also described, featuring examples of the data that can be generated and, importantly, how the data can be analysed. Furthermore, there are sections detailing tips, tricks and pitfalls to avoid, all written and peer-reviewed by leading experts in the field, making this an essential research companion.