A clinical microchip for evaluation of single immune cells reveals high functional heterogeneity in phenotypically similar T cells

Current approaches for analyzing the functional heterogeneity of immune cells include ELISPOT and flow cytometry. Chao Ma et al. have introduced an antibody-barcode microchip platform that enables the measurement of a large panel of secreted proteins from several hundred single cells or small cell colonies in parallel. The platform offers advantages over existing technologies in terms of cost, multiplexing capacity, types of proteins that can be measured and experiments performed. Cellular immunity has an inherent high level of functional heterogeneity. Capturing the full spectrum of these functions requires analysis of large numbers of effector molecules from single cells. We report a microfluidic platform designed for highly multiplexed (more than ten proteins), reliable, sample-efficient (∼1 × 104 cells) and quantitative measurements of secreted proteins from single cells. We validated the platform by assessment of multiple inflammatory cytokines from lipopolysaccharide (LPS)-stimulated human macrophages and comparison to standard immunotechnologies. We applied the platform toward the ex vivo quantification of T cell polyfunctional diversity via the simultaneous measurement of a dozen effector molecules secreted from tumor antigen–specific cytotoxic T lymphocytes (CTLs) that were actively responding to tumor and compared against a cohort of healthy donor controls. We observed profound, yet focused, functional heterogeneity in active tumor antigen–specific CTLs, with the major functional phenotypes quantitatively identified. The platform represents a new and informative tool for immune monitoring and clinical assessment.