In May 2023, we attended IMMUNOLOGY2023, the annual meeting of the American Association of Immunologists in Washington, DC, and recorded daily episodes discussing highlights of the previous 24 hours. Here is the first of five special episodes from the meeting, in which Jason and Brenda summarize symposia on B and T-helper cells, and metabolic and gut microbiota. They discuss antigenic imprinting, lupus immunophenotyping and sex differences, dengue vaccines, and cytomegalovirus research.