von Boehmer H, Shortman K
Aust J Exp Biol Med Sci. 1975 Aug;53(4):281-95.
Equilibrium density separation on continuous albumin gradients was used to separate and characterise the T cells responding by proliferation to both syngeneic and allogeneic stimulating cells in the one-way mixed leucocyte reactions (MLR). In CBA mouse spleen both light and dense T cells were capable of responding in an allogeneic MLR. No T cells responding to stimulation be syngeneic B lymphocytes could be isolated from adult or 7-day CBA mouse spleen. In adult CBA mouse thymus, cells responding to allogeneic stimuli were enriched in the light density region, along with the low theta subpopulation. Self-reactive cells, responding with proliferation when cultured with syngeneic adult CBA splenic lymphocytes, and found in adult and 4-day CBA mouse thymus, were also enriched in the light density zones. However, in adult thymus syngeneic MLR reactivity was also found in the dense zones, and the density distribution profiles of total syngeneic MLR responding cells revealed a series of peaks extending over the whole density range. It was suggested that these syngeneic MLR responders undergo a complete maturation process, including progressive density increases, within the thymus gland. Such a sterile differentiation pathway could be a censorship process, leading to death of self-reactive cells within the thymus.
利用连续白蛋白梯度进行平衡密度分离，以分离和鉴定在单向混合淋巴细胞反应（MLR）中对同基因和异基因刺激细胞产生增殖反应的T细胞。在CBA小鼠脾脏中，轻密度和高密度T细胞都能够在异基因MLR中做出反应。从成年或7日龄CBA小鼠脾脏中无法分离出对同基因B淋巴细胞刺激有反应的T细胞。在成年CBA小鼠胸腺中，对异基因刺激有反应的细胞与低θ亚群一起富集在轻密度区域。当与同基因成年CBA脾淋巴细胞一起培养时会发生增殖反应的自身反应性细胞，在成年和4日龄CBA小鼠胸腺中均有发现，它们也富集在轻密度区域。然而，在成年胸腺中，同基因MLR反应性也存在于高密度区域，并且对同基因MLR有反应的总细胞的密度分布曲线显示出一系列在整个密度范围内延伸的峰。有人提出，这些对同基因MLR有反应的细胞在胸腺内经历了一个完整的成熟过程，包括密度逐渐增加。这样一条无菌分化途径可能是一个审查过程，导致胸腺内自身反应性细胞死亡。
