Hannestad J, Germanà A, Catania S, Laurà R, Ciriaco E, Vega J A
Istituto di Anatomia degli Animali Domestici con Istologia e Embriologia, Facoltà di Medicina Veterinaria, Università di Messina, Italy.
Vet Immunol Immunopathol. 1998 Feb 27;61(2-4):359-67. doi: 10.1016/s0165-2427(97)00145-1.
Neurotrophins are growth factors which bind to signal-transducing receptors called Trk proteins. The neurotrophins and their receptor proteins are present in the mammalian and avian lymphoid organs, thus suggesting that these factors could act upon cells of the immune system. Nevertheless, little is known about the cellular distribution of neurotrophins and their receptor proteins in avian lymphoid tissues. In this study we use immunohistochemistry to detect the cellular localisation of neurotrophins and their receptor proteins in the pigeon caecal tonsil, used as a model for avian secondary lymphoid organs. Rabbit polyclonal antibodies against neurotrophins (nerve growth factor -NGF-, brain-derived neurotrophic factor -BDNF- and neurotrophin -3 NT-3-) and against specific epitopes of TrkA, TrkB and TrkC proteins were used. Cytokeratins, vimentin, S-100 protein and chromogranin A were studied in parallel to identify cells which seemed to express neurotrophins and Trk proteins. TrkA-like protein was seen in the intestinal epithelium, whereas TrkB-like and TrkC-like proteins was found in cells which we identified as dendritic cells and macrophages. BDNF-like and NT-3-like reactivity was localised in intestinal epithelial cells, especially endocrine cells. Present results add further evidence to the presumptive immune role of neurotrophins and their receptors and the possible functions of these peptides in the caecal tonsil are discussed.
神经营养因子是一类生长因子，它们可与称为Trk蛋白的信号转导受体结合。神经营养因子及其受体蛋白存在于哺乳动物和禽类的淋巴器官中，这表明这些因子可能作用于免疫系统的细胞。然而，关于神经营养因子及其受体蛋白在禽类淋巴组织中的细胞分布情况，人们了解得还很少。在本研究中，我们使用免疫组织化学方法来检测神经营养因子及其受体蛋白在鸽盲肠扁桃体中的细胞定位，鸽盲肠扁桃体被用作禽类二级淋巴器官的模型。我们使用了针对神经营养因子（神经生长因子-NGF-、脑源性神经营养因子-BDNF-和神经营养因子-3 NT-3-）以及针对TrkA、TrkB和TrkC蛋白特定表位的兔多克隆抗体。同时研究了细胞角蛋白、波形蛋白、S-100蛋白和嗜铬粒蛋白A，以识别那些似乎表达神经营养因子和Trk蛋白的细胞。在肠上皮细胞中可见TrkA样蛋白，而在我们鉴定为树突状细胞和巨噬细胞的细胞中发现了TrkB样和TrkC样蛋白。BDNF样和NT-3样反应定位于肠上皮细胞，尤其是内分泌细胞。目前的结果为神经营养因子及其受体的假定免疫作用提供了进一步的证据，并讨论了这些肽在盲肠扁桃体中的可能功能。
