Why does the thymus involute? A selection-based hypothesis.
Thymic involution remains a fundamental mystery in immunology. Here we present an argument that this seemingly counterproductive behavior may have evolved to allow for peripheral selection of a T-cell repertoire during young-adult life, optimized for fighting infections and avoiding reaction to self. Age-associated decline in immune function may be viewed as an unfortunate side effect of this selective process. Thus, the key to understanding thymic involution might lie in a more quantitative understanding of T-cell homeostasis in the periphery.
Dowling
Mark R
MR
Immunology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3050, Australia.
Hodgkin
Philip D
PD
D000328:Adult; D000375:Aging / Q000276:immunology*; D000818:Animals; D005075:Biological Evolution; D002454:Cell Differentiation / Q000276:immunology*; D006706:Homeostasis / Q000276:immunology*; D006801:Humans; D018448:Models, Immunological; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D013950:Thymus Gland / Q000276:immunology* / Q000378:metabolism; D055815:Young Adult