1. The (green) B cell has ingested an antigen and displayed part of it (bright yellow) on a molecule bound to cell surface. Once a T cell (blue) becomes activated by binding to the antigen/molecule complex on an infected or cancerous cell, it begins to divide rapidly, and differentiates into memory T cells and other subtypes of T cells. Some, called T helper cells, secrete chemical messengers known as cytokines or lymphokines(golden yellow), which mobilize many other cells and substances.

2. J. Michael Hamilton, M.D., preparing the carcinoembryonic antigen (CEA) vaccinia vaccine used to try to prevent cancer.