Applying Mass Cytometry to the Analysis of Lymphoid Populations in Transplantation

Single-cell flow cytometric techniques have been indispensable to improving our understanding of the phenotype and function of immune cell subsets that are important in both rejection and tolerance after transplant. Mass cytometry, or cytometry by time of flight, is a single-cell-based platform that utilizes antibodies conjugated to rare heavy metal ions for analysis of cellular proteins by a time-of-flight mass spectrometer. This new technology allows for the evaluation of >40 simultaneous cellular parameters in a single sample because the limitation of spectral overlap, seen in conventional flow cytometry, is eliminated. In this review, we discuss the current state of mass cytometry, describe the advantages and disadvantages compared with multiparameter flow cytometry, introduce novel methods of high-dimensional data analysis and visualization, and review some recent studies using mass cytometry to profile the immune systems of healthy people and transplant recipients.