Fig. 2

Dynamic and homeostatic control of lymphocytes in the periphery. Legend: Ag, LN, IL, and BAFF-R stand for antigen, lymph node, interleukin, and B-cell activating factor receptor, respectively. A Dynamic and homeostatic control of T-cells in the periphery. In rodents, the naïve T-cell level is maintained based on input to the thymus and survival signals, which are controlled by IL-7 and TCR signaling with MHC. The memory T-cell level is maintained by differentiation input from the naïve cell population and survival signals controlled by IL-7. Memory cells can proliferate or differentiate from the naïve population in case of lymphopenia. Effector cells differentiate from naïve T-cells following immune stimulation. Most effector cells die shortly after stimulation by apoptosis, and only a few differentiate into memory cells. B Dynamic and homeostatic control of B-cells in the periphery. The resting B-cell level is maintained by input from the spleen and survival signals, controlled by BCR signaling and B-cell activating factor receptor (BAFF-R). Activated B-cells either die after immune stimulation or differentiate into long-lived populations. The long-lived memory population can expand by proliferation or differentiation from the naïve population in case of lymphopenia. C Dynamic and homeostatic control of NK-cells in the periphery. The resting NK-cell level is maintained by input from primary lymphatic organs and survival signals, which are controlled by receptor signaling and IL-15. Activated NK-cells either die after immune stimulation or differentiate into long-lived populations