Dvorak P, Yoshiki A, Dvorakova D, Flechon J E, Kusakabe M
Laboratoire de Biologie Cellulaire et Moleculaire, INRA, Jouy en Josas, France.
Int J Dev Biol. 1995 Aug;39(4):645-52.
Two different inbred strain combinations of mouse aggregation chimeras - C3H/HeN (H-2k) x C57BL/6N (H-2b) and C3H/HeN x BALB/cA (H-2d) were used for cell mixing analysis at two points in time - 24 h after aggregation (just prior to transplantation into foster mothers) and 7.5 days post coitum (p.c.). The cell proportion of two H-2 haplotypes at the blastocyst stage was studied using a fluorescence-labeled monoclonal antibody recognizing a C3H-specific alloantigen - CSA (C3H strain-specific antigen) and laser scanning confocal microscopy. The 7.5-day-old chimeras were sectioned and subsequently processed by sensitive biotinylated antibody - avidin peroxidase immunohistochemical technique. Our results showed that 24 h after aggregation (blastocyst stage), there was equal cell mixing and no mouse strain used in the present study was dominant at this time. In 7.5-day-old C3H/HeN x BALB/cA chimeras, cells of both genotypes were intermingled, but the C3H/HeN strain was dominant in all cases. In contrast, the combination C3H/HeN x C57BL/6N clearly showed reduced numbers of C3H/HeN cells (CSA-positive) in 83% of the chimeras evaluated. Generally, CSA positive cells were found only in randomly distributed small distinct areas representing less than 20% of embryonal cells. Surprisingly, the extraembryonal ectoplacental cone was uniformly CSA positive in some C3H/HeN x C57BL/6N chimeras. Furthermore, in 36% of normally implanted chimeras of both strain combinations progressive degeneration was observed. We suggest that the cell mixing pattern as well as the absolute number of cells derived from each strain in the aggregation chimera can be affected by specific immune interactions involving H-2 haplotype combinations of the allogeneic fetus and the fully immunocompetent host organism, at later points in development.
采用两种不同的近交系小鼠聚集嵌合体组合——C3H/HeN（H-2k）×C57BL/6N（H-2b）和C3H/HeN×BALB/cA（H-2d），在两个时间点进行细胞混合分析——聚集后24小时（即将移植到代孕母鼠体内之前）和交配后7.5天（p.c.）。使用识别C3H特异性同种异体抗原——CSA（C3H品系特异性抗原）的荧光标记单克隆抗体和激光扫描共聚焦显微镜，研究囊胚期两种H-2单倍型的细胞比例。将7.5天大的嵌合体切片，随后采用灵敏的生物素化抗体-抗生物素蛋白过氧化物酶免疫组织化学技术进行处理。我们的结果表明，聚集后24小时（囊胚期），细胞混合均匀，本研究中使用的任何小鼠品系在此阶段均不占优势。 在7.5天大的C3H/HeN×BALB/cA嵌合体中，两种基因型的细胞相互混杂，但在所有情况下C3H/HeN品系占主导地位。相比之下，C3H/HeN×C57BL/6N组合在83%的评估嵌合体中明显显示C3H/HeN细胞（CSA阳性）数量减少。一般来说，CSA阳性细胞仅在随机分布的小而明显的区域中发现，占胚胎细胞的比例不到20%。令人惊讶的是，在一些C3H/HeN×C57BL/6N嵌合体中，胚外外胎盘锥均匀地呈CSA阳性。此外，在两种品系组合的36%正常着床的嵌合体中观察到进行性退化。我们认为，在发育后期，聚集嵌合体中细胞的混合模式以及来自每个品系的细胞绝对数量可能受到涉及同种异体胎儿和完全具有免疫活性的宿主生物体的H-2单倍型组合的特异性免疫相互作用的影响。
