Customizing Maxpar Direct Immune Profiling Assay with Additional Surface Marker and Intracellular Cytokine Staining Workflows for Expanded Mass Cytometry Panels.

Mass cytometry, or cytometry by time-of-flight (the basis for Fluidigm® CyTOF® technology), is a system for single-cell detection using antibodies tagged with metal probes. Without the need for compensation, the highly parametric Helios™ mass cytometer has a detection range of 135 distinct mass channels (75-209 Da). Optimized for mass cytometry, the Maxpar® Direct™ Immune Profiling Assay™ is a dry, metal-tagged antibody cocktail for immunophenotyping 37 immune cell populations found in human peripheral blood in a single tube. The Maxpar Direct Assay utilizes 31 mass channels for marker detection and live/dead viability staining, with at least 14 additional marker channels available from the Fluidigm catalog for flexible custom panel design. Here, we describe a workflow combining the assay with additional surface and intracellular cytokine antibodies for peripheral blood mononuclear cell (PBMC) staining using lanthanide-, bismuth-, and cadmium-tagged antibodies.

Imaging Mass Cytometry Analysis of immune Checkpoint Inhibitor-Related Pneumonitis: A Case Report.

Immune checkpoint inhibitor-related pneumonitis (CIP) is a rare but well-recognized immune-related adverse event (irAE), causes 35% of irAE related deaths. However, the mechanism of CIP remains unclear and no evidence-based treatment except for glucocorticoids is available. Herein, we report the case of a patient with metastatic bladder cancer who received tislelizumab and was diagnosed with CIP. The patient underwent transbronchial cryobiopsy. The patient was treated with glucocorticoid, but CIP recurred when the glucocorticoid tapering. The paraffine-embedded lung tissue was sectioned, stained with 31 heavy-metal tagged antibodies, and analyzed using imaging mass cytometry (IMC) technology. We identified multiple immune cell subsets in the lung tissue and observed the infiltration of memory T cells and the CD4+ DC subset. The data indicated the great potential of IMC technology in the identification and characterization of irAEs. Further investigation is warranted to identify the mechanism of action of CIP.