Farnoud M R, Derome P, Peillon F, Li J Y
Unité Inserm 223, Faculté de Médecine Pitié-Salpêtrière, Paris, France.
Lab Invest. 1994 Mar;70(3):399-406.
Laminin (LM) is an integral component of basement membranes (BM), with important roles in various aspects of cell biology. Several different isoforms of LM have been described, and each comprises a molecule consisting of three subunit polypeptides, the A, B1, B2, M or S chain.
The distribution of different LM subunits was studied in human nontumoral anterior pituitaries obtained postmortem and in pituitary adenomas by immunocytochemical methods using specific monoclonal antibodies.
In normal tissue, the A, B1, and B2 chains had a ubiquitous localization in both parenchymatous and vascular BMs and in the pericapillary connective tissue space also. The S chain seemed to have principally a vascular localization, in contrast to the M chain that was mostly localized in the parenchymatous BM. The same antigens were investigated in 23 human pituitary adenomas of different secretory type, grade and invasiveness. In all cases, the five monoclonal antibodies gave a positive staining. The presence or the localization of LM chains did not display a specific pattern in the adenomas according to their secretory type, grade or extent of local invasion. In the adenomas, the anti-A, -B1, and -B2 monoclonal antibodies stained the stroma and in particular the vascular BMs as well as the sparse elements of parenchymatous BMs when they were present. The staining with anti-S antibody was localized in the stroma and around all the blood vessels. In contrast, the immunoreactive material to anti-M antibody was associated to the sparse fragments of parenchymatous BMs and it delineated the boundary of adenoma cells and stroma. Within the stroma, the anti-M antibody immunoreactivity was regularly associated with the arterial walls but rarely with the venule walls.
The human normal and tumoral anterior pituitary express all five LM subunits and thus contain several LM isoforms with different patterns of localization. The most striking difference between the human normal and tumoral anterior pituitary concerns the peculiar expression of LM isoforms by adenomatous neovessels.
层粘连蛋白（LM）是基底膜（BM）的一个重要组成部分，在细胞生物学的各个方面发挥着重要作用。已经描述了几种不同的LM同工型，每种同工型都由一个由三个亚基多肽组成的分子构成，即A、B1、B2、M或S链。
使用特异性单克隆抗体，通过免疫细胞化学方法研究了不同LM亚基在死后获取的人非肿瘤性垂体前叶以及垂体腺瘤中的分布。
在正常组织中，A、B1和B2链在实质和血管基底膜以及毛细血管周围结缔组织间隙中均普遍存在。与主要定位于实质基底膜的M链相比，S链似乎主要定位于血管。对23例不同分泌类型、分级和侵袭性的人垂体腺瘤进行了相同抗原的研究。在所有病例中，五种单克隆抗体均呈阳性染色。根据腺瘤的分泌类型、分级或局部侵袭程度，LM链的存在或定位在腺瘤中未显示出特定模式。在腺瘤中，抗A、抗B1和抗B2单克隆抗体对基质进行染色，特别是血管基底膜以及存在的实质基底膜的稀疏成分。抗S抗体染色定位于基质和所有血管周围。相比之下，抗M抗体的免疫反应物质与实质基底膜的稀疏片段相关，并勾勒出腺瘤细胞和基质的边界。在基质内，抗M抗体免疫反应性通常与动脉壁相关，但很少与小静脉壁相关。
人正常和肿瘤性垂体前叶均表达所有五种LM亚基，因此含有几种具有不同定位模式的LM同工型。人正常和肿瘤性垂体前叶之间最显著的差异在于腺瘤性新生血管中LM同工型的特殊表达。
