Automated cell processing for mass cytometry experiments

Abstract

Mass cytometry is a powerful technology for high-dimensional single-cell measurements in millions of individual cells. Antibodies and other detection probes are coupled to elemental tags, each with a unique mass and detectable at single-cell resolution using an ICP-MS type of instrument. Given the sensitivity of the detection system, any free metal ions must be carefully removed through multiple rounds of washing in order to prevent background signal. This results in significant loss of cells. Together with cells lost during acquisition, the final data can represent as little as 10% of the starting material, seriously limiting the amount of information that can be extracted from small samples. Furthermore, complex staining protocols introduce experimental variations that limit comparisons across experiments. Here we present a cell processing and staining procedure for mass cytometry fully automated using a liquid handling robotic system and we present measures taken to optimize all steps of the protocol. These advances are applicable to both manual and automated protocols and provide a six-fold higher cell yield as compared to a standard protocol. With this increased yield and improved reproducibility this protocol now allows us to perform mass cytometry analysis using as little as 100 μL of whole blood as starting material.