Tilemans D, Vijver V V, Verhoeven G, Denef C
Laboratory of Cell Pharmacology, University of Leuven School of Medicine, Belgium.
J Histochem Cytochem. 1995 Jul;43(7):657-64. doi: 10.1177/43.7.7608520.
Using a specific anti-rat transferrin (Tf) antiserum, Tf-like immunoreactivity (Tf-lir) was detected by immunostaining in intact rat pituitaries and in reaggregated pituitary cells cultured in serum-free medium. Tf-lir cells were present in the anterior pituitary (AP), and in the intermediate (IL) and neural lobes (NL). In the AP, Tf-lir cells were oval or polygonal. An unusual topographical distribution was found. Tf-lir cells mainly occurred as dense clusters in the lateral wings. In the central part of the AP, Tf-lir was found in flattened perisinusoidal cells. Double immunostaining for Tf and the different pituitary hormones showed that Tf-lir co-localized with some gonadotrophs and somatotrophs (7% and 3% of Tf-lir cells, respectively, in typical sections). No co-localization was seen with PRL, ACTH, TSH, or alpha-MSH. The distribution of Tf-lir cells and their cell shape completely differed from that of S-100-positive cells in the AP. In the IL, clusters of large stellate Tf-lir cells were found. Again, their distribution completely differed from S-100-positive cells. In the NL, diffuse staining was found. Double immunostaining of paraffin-embedded sections of reaggregate cell cultures of the AP did not reveal any co-localization of Tf-lir with ACTH, alpha-MSH, LH, FSH, TSH, GH, or PRL. In aggregates consisting of NL + IL cells, Tf-lir was located in clusters: no co-localization with ACTH or alpha-MSH could be demonstrated. Reaggregate cell cultures of AP and NL + IL secreted Tf-lir as measured by radioimmunoassay, at least during 21 days of culture. After metabolic labeling with [35S]-methionine and immunoprecipitation of [35S]-methionine-labeled material present in the culture medium of both AP and NL + IL aggregates with anti-Tf antiserum, a 35S-labeled substance was found, which on SDS-PAGE showed an apparent M(r) of approximately 78 KD, corresponding to the M(r) of rat Tf. The present data show that a specific population of cells of rat anterior pituitary is capable of synthesizing, storing, and secreting transferrin or a substance closely related to it. Cells different from melanotrophs and S-100 cells in the IL, as well as pituicytes in the NL, also appear to produce this material. We suggest that transferrin or a transferrin-like substance may have a local role in the transport of iron or other metals or may play a role as growth factor in the three lobes of the pituitary gland.
利用一种特异性抗大鼠转铁蛋白（Tf）抗血清，通过免疫染色在完整大鼠垂体以及在无血清培养基中培养的重新聚集的垂体细胞中检测到了Tf样免疫反应性（Tf-lir）。Tf-lir细胞存在于腺垂体（AP）、中间叶（IL）和神经垂体（NL）中。在腺垂体中，Tf-lir细胞呈椭圆形或多边形。发现了一种不寻常的拓扑分布。Tf-lir细胞主要以密集簇状出现在侧翼。在腺垂体中央部分，扁平的窦周细胞中发现了Tf-lir。对Tf和不同垂体激素进行双重免疫染色显示，Tf-lir与一些促性腺激素细胞和生长激素细胞共定位（在典型切片中，分别占Tf-lir细胞的7%和3%）。未观察到与催乳素、促肾上腺皮质激素、促甲状腺激素或α-促黑素的共定位。腺垂体中Tf-lir细胞的分布及其细胞形状与S-100阳性细胞完全不同。在中间叶，发现了大的星状Tf-lir细胞簇。同样，它们的分布与S-100阳性细胞完全不同。在神经垂体中，发现了弥漫性染色。对腺垂体重新聚集细胞培养物的石蜡包埋切片进行双重免疫染色未显示Tf-lir与促肾上腺皮质激素、α-促黑素、促黄体生成素、促卵泡激素、促甲状腺激素、生长激素或催乳素的任何共定位。在由神经垂体+中间叶细胞组成的聚集体中，Tf-lir位于簇中：未证明与促肾上腺皮质激素或α-促黑素的共定位。通过放射免疫测定，腺垂体和神经垂体+中间叶的重新聚集细胞培养物至少在培养21天期间分泌Tf-lir。用[35S]-甲硫氨酸进行代谢标记并用抗Tf抗血清对腺垂体和神经垂体+中间叶聚集体培养基中存在的[35S]-甲硫氨酸标记物质进行免疫沉淀后，发现了一种35S标记物质，其在SDS-PAGE上显示的表观分子量约为78 KD，与大鼠Tf的分子量相对应。目前的数据表明，大鼠腺垂体的特定细胞群能够合成、储存和分泌转铁蛋白或与其密切相关的物质。中间叶中不同于黑素细胞和S-100细胞的细胞以及神经垂体中的垂体细胞似乎也产生这种物质。我们认为转铁蛋白或转铁蛋白样物质可能在铁或其他金属的运输中起局部作用，或者可能在垂体的三个叶中作为生长因子发挥作用。
