Nilsson G, Forsberg-Nilsson K, Xiang Z, Hallböök F, Nilsson K, Metcalfe D D
Laboratory of Allergic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, USA.
Eur J Immunol. 1997 Sep;27(9):2295-301. doi: 10.1002/eji.1830270925.
Mast cells are the principal effector cells in IgE-dependent hypersensitivity reactions. Despite reports that rodent mast cells proliferate in the presence of nerve growth factor (NGF), human mast cells reportedly do not respond to this factor. To determine if human mast cells express the NGF receptors, TrkA tyrosine receptor and the low affinity NGF receptor (LNGFR), we first analyzed the mRNA expression by RT-PCR of TrkA and LNGFR in a human mast cell line (HMC-1) and in human mast cells cultured in the presence of stem cell factor. Both HMC-1 and cultured human mast cells were found to express TrkA but not LNGFR. TrkA protein was demonstrated by Western blot analysis of HMC-1 lysates. Using flow cytometric analysis and mast cell tryptase as a mast cell marker, both HMC-1 cells and cultured human mast cells were shown to coexpress tryptase and TrkA. Treatment of mast cells with NGF resulted in phosphorylation of TrkA on tyrosine residues as detected by immunoblotting with an antiphosphotyrosine antibody. Furthermore, NGF induced the immediate early gene c-fos in HMC-1 cells. HMC-1 cells and cultured human mast cells were also found to express NGF mRNA, and conditioned medium from HMC-1 cells stimulated neurite outgrowth from chicken embryonic sensory ganglia in culture. This effect was blocked by anti-NGF. Thus, mast cells express functional TrkA and synthesize NGF, suggesting a mechanism by which NGF may act as an autocrine factor for human mast cells, and by which mast cells and nerves may interact.
肥大细胞是IgE依赖性超敏反应中的主要效应细胞。尽管有报道称啮齿动物肥大细胞在神经生长因子（NGF）存在下会增殖，但据报道人类肥大细胞对该因子无反应。为了确定人类肥大细胞是否表达NGF受体、TrkA酪氨酸受体和低亲和力NGF受体（LNGFR），我们首先通过RT-PCR分析了人肥大细胞系（HMC-1）以及在干细胞因子存在下培养的人肥大细胞中TrkA和LNGFR的mRNA表达。结果发现HMC-1和培养的人肥大细胞均表达TrkA但不表达LNGFR。通过对HMC-1裂解物进行蛋白质印迹分析证实了TrkA蛋白的存在。使用流式细胞术分析并以肥大细胞类胰蛋白酶作为肥大细胞标志物，结果显示HMC-1细胞和培养的人肥大细胞均共表达类胰蛋白酶和TrkA。用NGF处理肥大细胞后，通过抗磷酸酪氨酸抗体免疫印迹检测发现TrkA的酪氨酸残基发生了磷酸化。此外，NGF诱导HMC-1细胞中即早基因c-fos的表达。还发现HMC-1细胞和培养的人肥大细胞表达NGF mRNA，并且HMC-1细胞的条件培养基可刺激培养的鸡胚感觉神经节的神经突生长。这种效应可被抗NGF阻断。因此，肥大细胞表达功能性TrkA并合成NGF，这表明NGF可能作为人类肥大细胞的自分泌因子发挥作用，以及肥大细胞与神经之间可能相互作用的一种机制。
