Department of Anatomy, Embryology and Histology, Faculty of Veterinary Medicine, Assiut University, Assiut, 71526, Egypt.
Sci Rep. 2021 Jan 13;11(1):872. doi: 10.1038/s41598-020-79529-y.
Dendritic cells (DCs) are innate immune cells which engulf, process and present antigens to the naïve T-lymphocyte cells. However, little is known about the effect of melatonin on the DCs. The present study aimed to investigate the morphology and distribution of the DCs by transmission electron microscopy and Immunohistochemistry after melatonin administration. A total of 8 out of 15 adult ram was randomly selected to receive the melatonin implant and the remaining 7 animals received melatonin free implants. DCs showed positive immunoreactivity for CD117, S-100 protein and CD34. There is an obvious increase in the number of the positive immunoreactive cells to CD3, estrogen receptor alpha and progesterone in the treated groups. The expression of CD56 and MHCII in the DCs was abundant in the treated groups. The ultrastructure study revealed that melatonin exerts a stimulatory effect on the DCs which was associated with increment in the secretory activity of DCs. The secretory activity demarcated by an obvious increase in the number of mitochondria, cisternae of rER and a well-developed Golgi apparatus. The endosomal- lysosomal system was more developed in the treated groups. A rod-shaped Birbeck granule was demonstrated in the cytoplasm of the melatonin treated group. DCs were observed in a close contact to telocytes, T-Lymphocytes, nerve fibers and blood vessels. Taken together, melatonin administration elicits a stimulatory action on the DCs and macrophages through increasing the size, the number and the endosomal compartments which may correlate to increased immunity.
树突状细胞（DCs）是先天免疫细胞，可吞噬、加工和向幼稚 T 淋巴细胞呈递抗原。然而，关于褪黑素对 DCs 的影响知之甚少。本研究旨在通过透射电镜和免疫组织化学观察褪黑素给药后 DCs 的形态和分布。从 15 只成年公羊中随机选择 8 只接受褪黑素植入，其余 7 只接受无褪黑素植入。DCs 对 CD117、S-100 蛋白和 CD34 呈阳性免疫反应。与对照组相比，治疗组 CD3、雌激素受体α和孕激素的阳性免疫反应细胞数量明显增加。DCs 中 CD56 和 MHCII 的表达在治疗组中丰富。超微结构研究表明，褪黑素对 DCs 具有刺激作用，这与 DCs 分泌活性的增加有关。分泌活性表现为线粒体、内质网池和发达的高尔基体数量明显增加。内体-溶酶体系统在治疗组中更为发达。在褪黑素治疗组的细胞质中观察到棒状 Birbeck 颗粒。DCs 与间质细胞、T 淋巴细胞、神经纤维和血管密切接触。综上所述，褪黑素给药通过增加 DCs 和巨噬细胞的大小、数量和内体隔室，对其产生刺激作用，这可能与增强免疫力有关。
