A Versatile High‐Throughput Single‐Cell Screening Platform for Profiling Antigen‐Specific Long‐Lived B Cells in Blood and Bone Marrow

Abstract Antigen‐specific B cells play a crucial role in the long‐term immune response following infection or vaccination, differentiating into antibody‐secreting cells (ASCs) and memory B cells (MBCs). However, profiling ASCs is challenging primarily due to their lack of membrane‐bound surface B cell receptors. In this study, the Modular Superhydrophobic Microwell Array Chip (MoSMAR‐chip) is introduced as a versatile, cost‐effective, and high‐throughput platform for identifying and characterizing individual antigen‐specific ASCs and MBCs at the single‐cell level within seven days. Using this platform, comprehensive analyses of single ASCs could be performed from bone marrows of coronavirus disease 2019 (COVID‐19) vaccine‐immunized mice and a diverse set of antibodies capable of neutralizing the highly divergent JN1 variant of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) were identified. These results demonstrate that the MoSMAR‐chip facilitates efficient single‐cell multi‐omics and functional analyses of antigen‐specific ASCs, offering a powerful tool for investigating complex long‐term B cell immunity in diverse clinical conditions, such as infectious diseases, autoimmunity, and beyond.