Durandy A
U 132 INSERM, Hôpital des Enfants-Malades, Paris, France.
Pathol Biol (Paris). 1992 Sep;40(7):685-9.
The development of immune defense mechanisms begins early during fetal life but is not yet completed at birth. The earliest hematopoietic stem cells, which give rise to the lymphocytic and myelomonocytic cell lines, appear between the fourth and eight weeks postconception. T cells, responsible for cellular immune defense mechanisms, are first detectable at 12 weeks and seem to acquire their functional capabilities at the 16th week. B lymphocytes, responsible for humoral immunity, can be identified in the fetal liver at eight weeks and are functional at the 12-th-13th week, with the ability to produce specific IgM antibodies. Thus, in theory, fetuses of more than 16 weeks can produce a full immune response. Neonates still have incomplete development of a number of mechanisms involved in nonspecific immunity (natural killer, polynuclear and macrophage chemo-attraction, complement system).
免疫防御机制的发育在胎儿期早期就已开始，但出生时仍未完成。最早产生淋巴细胞和髓单核细胞系的造血干细胞在受精后第四至八周出现。负责细胞免疫防御机制的T细胞在12周时首次可检测到，并似乎在第16周获得其功能能力。负责体液免疫的B淋巴细胞在8周时可在胎儿肝脏中识别，并在第12 - 13周时发挥功能，具有产生特异性IgM抗体的能力。因此，理论上，超过16周的胎儿可以产生完全的免疫反应。新生儿在涉及非特异性免疫的一些机制（自然杀伤细胞、多核细胞和巨噬细胞趋化作用、补体系统）方面仍发育不完全。
