Sugimoto M, Nakanishi Y, Otokawa M, Uchida N, Yasuda T, Sato H, Sato Y
J Immunol. 1983 Jun;130(6):2767-74.
The effect of highly purified leukocytosis (lymphocytosis)-promoting factor (LPF) of Bordetella pertussis on physical lymphocyte and reticuloepithelial (RE) cell association was studied in an in vitro thymus model. First, a simplified in vitro system to assess the lympho-RE-cell association was developed. A completely confluent layer of thymic RE cells was formed by cultivating trypsinized thymus cell suspensions from 2- to 7-day-old mice. When thymic lymphoid cells were seeded on this cell layer and cultivated overnight, a significant proportion of them were found underneath the RE cell layer. This physical lympho-RE-cell association was quantitated by counting the lymphoid cells underneath the RE cell layers. Second, the effect of LPF on this physical lympho-RE-cell association phenomenon was investigated. Addition of LPF to the culture markedly inhibited the formation of the lympho-RE-cell complex; that is, it inhibited the infiltration of lymphoid cells under the RE cell layer. LPF rendered a nearly maximal level of inhibitory effect at a dose of 0.1 ng/ml. Furthermore, LPF enhanced the liberation of lymphoid cells from preformed lympho-RE-cell complexes. On the other hand, LPF had no direct cytotoxic effect on lymphoid cells at doses below 1 microgram/ml. In order to investigate whether LPF produced the effect by acting on lymphoid cells, RE cells, or both, the following experiments were performed. When lymphoid cells were pretreated with LPF and added to normal RE cell layers, the lympho-RE-cell association was maximally inhibited above the dose of 1 ng/ml. Treatment of these LPF-treated lymphoid cells with anti-LPF antibodies failed to abrogate the effect of LPF. When RE cell layers were similarly pretreated with LPF and were cultivated with normal lymphoid cells, however, much higher doses of LPF, above 100 ng/ml, were required for maximal inhibition. Furthermore, treatment of these LPF-treated RE cells with anti-LPF antibodies abrogated the effect of LPF. Therefore, the apparent effect of LPF on RE cells was considered to be due to the carry-over by RE cells of LPF, which should directly act on lymphoid cells at extremely low doses. On the basis of these results, it was concluded that LPF acted directly on lymphoid cells without mediation of RE cells. These in vitro results appear to parallel the effects of LPF in vivo, where it induces a depletion of cells in the thymus. The model may be useful to study this phenomenon and the concomitant accumulation of blood lymphocytes.
在体外胸腺模型中研究了百日咳博德特氏菌高度纯化的白细胞增多（淋巴细胞增多）促进因子（LPF）对物理性淋巴细胞与网状上皮（RE）细胞结合的影响。首先，开发了一种简化的体外系统来评估淋巴细胞与RE细胞的结合。通过培养2至7日龄小鼠胰蛋白酶消化的胸腺细胞悬液，形成了一层完全汇合的胸腺RE细胞层。当将胸腺淋巴细胞接种在该细胞层上并培养过夜时，发现其中很大一部分位于RE细胞层下方。通过计数RE细胞层下方的淋巴细胞对这种物理性淋巴细胞与RE细胞的结合进行定量。其次，研究了LPF对这种物理性淋巴细胞与RE细胞结合现象的影响。向培养物中添加LPF可显著抑制淋巴细胞与RE细胞复合物的形成；也就是说，它抑制了淋巴细胞在RE细胞层下方的浸润。LPF在剂量为0.1 ng/ml时产生了几乎最大程度的抑制作用。此外，LPF增强了淋巴细胞从预先形成的淋巴细胞与RE细胞复合物中的释放。另一方面，LPF在剂量低于1微克/毫升时对淋巴细胞没有直接的细胞毒性作用。为了研究LPF是通过作用于淋巴细胞、RE细胞还是两者来产生这种作用的，进行了以下实验。当用LPF预处理淋巴细胞并将其添加到正常RE细胞层时，在剂量高于1 ng/ml时淋巴细胞与RE细胞的结合受到最大程度的抑制。用抗LPF抗体处理这些经LPF处理的淋巴细胞未能消除LPF的作用。然而，当用LPF对RE细胞层进行类似预处理并与正常淋巴细胞一起培养时，需要高于100 ng/ml的更高剂量的LPF才能达到最大抑制。此外，用抗LPF抗体处理这些经LPF处理的RE细胞消除了LPF的作用。因此，LPF对RE细胞的明显作用被认为是由于RE细胞对LPF的携带，LPF应在极低剂量下直接作用于淋巴细胞。基于这些结果，得出结论：LPF直接作用于淋巴细胞，无需RE细胞介导。这些体外结果似乎与LPF在体内的作用相似，在体内它会导致胸腺细胞减少。该模型可能有助于研究这种现象以及伴随的血液淋巴细胞积累。
