A discussion of immune tolerance and the layered immune system hypothesis

摘要

CC Anderson, critique. Essentially, the question being posed in the review of Mold and McCune1 is whether the fetaleonatal immune system has special properties that predispose it to tolerance. Why do antigens introduced early in life induce tolerance? The authors' answer is the "layered immune system" that mechanistically involves a preponderance of Treg early in life. This reviewer agrees that there are likely to be differences between the fetus and adult that help the fetus establish tolerance and immune system homeostasis. The authors identify some of these factors and others are likely to be found with further studies. Even our own studies have suggested a factor that may help in the establishment of tolerance in the fetuseonate, with the lack of mature lymph nodes restraining homeostatic activation when T cells first seed the periphery.2 Nevertheless, my main question is whether these differences between the fetus and adult are central to the question of how the decision between immunity and tolerance is made.