Neonates Support “Homeostatic” Proliferation
The number of lymphocytes in the periphery is maintained at a constant level throughout life. Positive or negative disturbances of such balance by either antigenic challenge or lymphoablative therapies lead to activation of homeostatic regulatory processes including massive activation-induced cell death and homeostatic proliferation of peripheral T cells, respectively (Marrack et al., 2000). Experimentally, it has been well demonstrated that lymphopenic environments generated by irradiation or genetic manipulation drives the proliferation of transferred na ve T cells, which rarely divide in their normal environment (Goldrath and Bevan, 1999). It has been argued that this process is fundamentally different from antigen-driven proliferation, implying that different mechanisms are involved (Clarke and Rudensky, 2000). Both the physiologic significance and mechanisms of homeostatic proliferation are poorly understood.
KeywordsEarly Postnatal Life Homeostatic Proliferation Thymic Selection Thymic Output Negative Disturbance
Unable to display preview. Download preview PDF.
- Garcia, A. M., Fadel, S. A., Cao, S., and Sarzotti, M., 2000, T cell immunity in neonates, Immunol. Res. 22:177.Google Scholar
- Marrack, P., Bender, J., Hildeman, D., Jordan, M., Mitchell, T., Murakami, M., Sakamoto, A., Schaefer, B. C., Swanson, B., and Kappler, J., 2000, Homeostasis of ab TCR+ T cells, Nat. Immunol. 1:107.Google Scholar
- Schluns, K. S., Kieper, W. C., Jameson, S. C., and Lefrancois, L., 2000, Interleukin-7 mediates the homeostasis of na ve and memory CD8 T cells in vivo, Nat. Immunol. 1:426.Google Scholar