The immune system has evolved elaborate mechanisms to respond to diverse antigens
while minimizing the risk for autoimmune reactivity. During lymphopenia, however, some
mechanisms that normally serve to maintain host tolerance are temporarily suspended.
Peripheral T cells proliferate in response to self-antigens in lymphopenic hosts, but
proliferation toward these same antigens is prevented when T cell numbers are normal. This
process, termed homeostatic peripheral expansion, augments peripheral T cell number and …