Recognition Activation Effector Decline Memory phase phase phase (homeostasis) Antibody. Effector T producing lymphocyte Elimination cell of antigens Humoral immunity Surviving memory Cell-mediated cells immunity Apoptosis Time after antigen exposure Figure 1-6 Phases of adaptive immune responses Adaptive immune responses consist of three phases: the recognition of antigen, the activation of lymphocytes, and the effector phase (elimination of antigen). The response declines as antigen-stimulated lymphocytes die by apoptosis, and the antigen-specific cells that survive are responsible for memory. The duration of each phase may vary in different immune responses. The y-axis represents an arbitrary measure of the magnitude of the response. These principles apply to humoral immunity (mediated by B lymphocytes) and cell-mediated immunity (mediated by T lymphocytes)