Cell-laden microwells for the study of multicellularity in lymphocyte fate decisions

Cell–cell cooperativity in populations of motile and transiently interacting immune cells has been difficult to assess in the absence of tools to control proximity and communication. Here, we describe the generation of cell-laden microwells that can precisely control contact-mediated interactions and multicellular ‘quorum’ decisions in lymphocytes. Different types of fate decisions for activating T cells can be shown to variously obey ‘binary’ or ‘density’ outcomes, correlated with cell–cell contact, using this new platform.