Figure 4. Rejuvenating immunity by inhibiting hyperfunction. (A) Specific hyper-functional cells (or signaling pathways) can inhibit some other cell types (or pathways) that are needed for proper anti-viral response and immunization. (B) By inhibiting hyper-functional cells or pathways, rapamycin can reactivate “loss-of-function” otherwise suppressed by hyper-functional cells or pathways.