This Funding Opportunity Announcement (FOA) seeks to solicit applications from interdisciplinary teams to participate in the Cooperative Centers on Human Immunology (CCHI) program. The program supports mechanistic and hypothesis-testing studies to discover novel molecules, mechanisms, or regulatory pathways governing function of the human immune system in both healthy and vulnerable populations (i.e., across lifespan, organ/tissue transplant recipients, pregnant women). Studies of interest include immunity related to prevention or treatment of infectious diseases, immune-mediated pathogenesis/sequelae associated with infectious disease, and/or immune-mediated diseases. This FOA also supports technology development to advance studies of the human immune system. The overarching goal of the CCHI is to provide foundational information on human immune system function to support translation of immunology research into clinical benefits.