Rigor and Reproducibility of Cytometry Practices for Immuno-Oncology: A multifaceted challenge

The rapid advancement of immunotherapy strategies has created a need for technologies that can reliably and reproducibly identify rare populations, detect subtle changes in modulatory signals, and assess antigenic expression patterns that are time-sensitive. Accomplishing these tasks requires careful planning and the employment of tools that provide greater sensitivity and specificity without demanding extensive time. Flow Cytometry has earned its place as a preferred analysis platform. This technology offers a flexible path to the interrogation of protein expression patterns and detection of functional properties in cell populations of interest. Mass Cytometry is a newcomer technology that has generated significant interest in the field. By incorporating mass spectrometry analysis to the traditional principles of flow cytometry, this innovative tool promises to significantly expand the ability to detect multiple proteins on a single cell. The use of these technologies in a manner that is consistent and reproducible through multiple sample sets demands careful attention to experiment design, reagent selection, and instrumentation. Whether applying flow or mass cytometry, reaching successful, reliable results involves many factors. Sample preparation, antibody titrations, and appropriate controls are major biological considerations that impact cytometric analysis. Additionally, instrument voltages, lasers, and run quality assessments are essential for ensuring comparability and reproducibility between analyses. In this article, we aim to discuss the critical aspects that impact flow cytometry, and will touch on important considerations for mass cytometry as well. Focusing on their relevance to immunotherapy studies, we will address the importance of appropriate sample processing and will discuss how selection of suitable panels, controls, and antibodies must follow a carefully designed plan. We will also comment on how educated use of instrumentation plays a significant role in the reliability and reproducibility of results.Through this work, we hope to contribute to the effort toward establishing higher standards for rigor and reproducibility of cytometry practices by researchers, operators, and general cytometry users employing cytometry-based assays in their work. © 2019 International Society for Advancement of Cytometry.