科学家在近期《自然—免疫学》杂志上撰文称，他们通过对小鼠进行研究，发现了婴儿的病毒感染抵抗力低的一种原因。
自然杀伤（NK）细胞是一种能帮助抵抗病毒感染的白细胞。这种细胞在感染早期病毒数量有限的情况下具有非常重要的作用。
Yasmina Laouar等人注意到，年幼小鼠和人类婴儿一样，因为缺乏成熟的NK细胞而对病毒更敏感。随后，他们发现TGF-β因子限制着未成熟NK细胞前体的增殖并阻碍其发育成熟。那些对TGF-β因子没有应答的新生和年幼小鼠能够产生有效的NK细胞并抵御病毒感染。虽然TGF-β因子一般被认为是通过阻止炎症发生来起到保护个体的作用，但在幼年小鼠体内，该因子却会阻止那些保护小鼠不受病毒感染的有利免疫应答反应。科学家接下来还需通过进一步试验确认该结论能否同样适用在人身上。（生物谷Bioon.com）
doi:10.1038/ni.2388
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TGF-β is responsible for NK cell immaturity during ontogeny and increased susceptibility to infection during mouse infancy
Jeffrey P Marcoe, James R Lim, Keri L Schaubert, Nassima Fodil-Cornu, Marsel Matka, Alexandra L McCubbrey, Alexander R Farr, Silvia M Vidal Yasmina Laouar
A large gap in our understanding of infant immunity is why natural killer (NK) cell responses are deficient, which makes infants more prone to viral infection. Here we demonstrate that transforming growth factor-β (TGF-β) was responsible for NK cell immaturity during infancy. We found more fully mature NK cells in CD11cdnR mice, whose NK cells lack TGF-β receptor (TGF-βR) signaling. Ontogenic maturation of NK cells progressed faster in the absence of TGF-β signaling, which results in the formation of a mature NK cell pool early in life. As a consequence, infant CD11cdnR mice efficiently controlled viral infections. These data thus demonstrate an unprecedented role for TGF-β in ontogeny that can explain why NK cell responses are deficient early in life.
