Hiramine C, Hojo K, Koseto M, Nakagawa T, Mukasa A
Department of Immunology and Immunopathology, Kagawa Medical School, Japan.
Lab Invest. 1990 Jan;62(1):41-54.
A thymic epithelial cell (TEC) line (B/c. TEC-L1) was established from a normal thymus of a 4-week BALB/c mouse. The B/c. TEC-L1 had an epithelial morphology showing a contact-inhibited cobblestone-like arrangement with occasional desmosome-like structures at the adjacent cellular membranes. B/c.TEC-L1 cells showed positive staining for desmosomal glycoprotein, cytokeratin, thymosin alpha 1 beta 3, and I-Ad, and MHC class I antigens. The doubling time was 24 hours, and the chromosome number ranged from 52 to 78 with the mode of 70. Coculture of B/c.TEC-L1 cells with syngeneic, peanut agglutinin-agglutinated (PNA+) thymocytes in suspension at 37 degree C was followed by the formation of TEC thymocyte rosettes, after which the reconstitution of thymic nurse cells ensued. At 4 degrees C, PNA+ thymocytes bound to the B/c.TEC-L1 cell but did not form thymic nurse cells. PNA- thymocytes, although to a lesser degree than PNA+ cells, bound to the TECs at 37 degrees C, but at 4 degrees C few cells bound to the TECs. Allogeneic thymocytes also bound to the TECs at 37 degrees C. When the PNA+ thymocytes were cultured on the B/c.TEC-L1 monolayer, the small ones chiefly adhered on the surface of the TECs, while underneath the TECs the relatively large thymocytes (including cells in mitosis) predominated. Although the PNA- thymocytes bound to the surface of the monolayer within a few hours after coculture, by 24 hours nearly all cells disappeared. It is presumed that the thymocytes creeping underneath the B/c.TEC-L1 monolayer and those enveloped within the thymic nurse cell reconstituted in the suspension culture; both may be placed in circumstances analogous to the thymic microenvironment, wherein immature thymocytes appear to contact TECs directly and to be exposed to higher concentrations of thymic hormones and other soluble factors. Additionally, cell death in the PNA+ thymocytes was also observed in the coculture with B/c.TEC-L1 cells. The PNA+ cells revealed the morphological changes termed "apoptosis" characterized by chromatin condensation and nuclear fragmentation.
从4周龄BALB/c小鼠的正常胸腺中建立了一种胸腺上皮细胞（TEC）系（B/c.TEC-L1）。B/c.TEC-L1具有上皮形态，呈接触抑制的鹅卵石样排列，相邻细胞膜处偶尔可见桥粒样结构。B/c.TEC-L1细胞桥粒糖蛋白、细胞角蛋白、胸腺素α1β3和I-Ad以及MHC I类抗原染色呈阳性。其倍增时间为24小时，染色体数在52至78之间，众数为70。将B/c.TEC-L1细胞与同基因的、花生凝集素凝集的（PNA+）胸腺细胞在37℃悬浮共培养后，形成了TEC胸腺细胞玫瑰花结，随后胸腺哺育细胞得以重建。在4℃时，PNA+胸腺细胞与B/c.TEC-L1细胞结合，但未形成胸腺哺育细胞。PNA-胸腺细胞虽然与PNA+细胞相比程度较低，但在37℃时与TEC结合，而在4℃时几乎没有细胞与TEC结合。同种异体胸腺细胞在37℃时也与TEC结合。当PNA+胸腺细胞在B/c.TEC-L1单层上培养时，小的细胞主要粘附在TEC表面，而在TEC下方相对较大的胸腺细胞（包括处于有丝分裂的细胞）占主导。虽然PNA-胸腺细胞在共培养后数小时内与单层表面结合，但到24小时时几乎所有细胞都消失了。据推测，在B/c.TEC-L1单层下方爬行的胸腺细胞以及在悬浮培养中重建的胸腺哺育细胞内包裹的胸腺细胞；两者可能处于类似于胸腺微环境的环境中，在该环境中未成熟胸腺细胞似乎直接接触TEC并暴露于更高浓度的胸腺激素和其他可溶性因子。此外，在与B/c.TEC-L1细胞共培养时也观察到PNA+胸腺细胞中的细胞死亡。PNA+细胞表现出称为“凋亡”的形态学变化，其特征为染色质浓缩和核碎片化。
