Conrad D H, Keegan A, Rao M, Lee W T
Int Arch Allergy Appl Immunol. 1987;82(3-4):402-4. doi: 10.1159/000234238.
The synthesis and ligand-dependent regulation of the lymphocyte receptor for IgE (Fc epsilon R) has been studied. Using murine Fc epsilon R+ cell lines, a 44-kilodalton 35S-methionine-labeled Fc epsilon R precursor was isolated by immunoaffinity chromatography. In contrast to the final processed 49-kilodalton Fc epsilon R, this precursor cannot be isolated from IgE affinity columns, indicating the importance of this processing in the function of the Fc epsilon R. The IgE-mediated Fc epsilon R upregulation was also studied and it was demonstrated that the degradation rate of the Fc epsilon R was dramatically slowed by ligand occupation of the Fc epsilon R. This degradation involves the cell surface-mediated release of a 38-kilodalton Fc epsilon R fragment that can be isolated using monoclonal anti-Fc epsilon R antibodies. Thus, these results demonstrate that posttranslational processing is required for the lymphocyte receptor to gain significant IgE-binding capacity; once acquired its degradation is slowed by occupation of the Fc epsilon R with ligand. At least in the rodent model system, this slowing of the degradation helps explain the increased Fc epsilon R levels seen in the presence of high IgE levels.
对IgE淋巴细胞受体（FcεR）的合成及配体依赖性调节进行了研究。利用小鼠FcεR⁺细胞系，通过免疫亲和层析分离出一种44千道尔顿的³⁵S-甲硫氨酸标记的FcεR前体。与最终加工后的49千道尔顿FcεR不同，这种前体无法从IgE亲和柱中分离出来，这表明这种加工在FcεR功能中的重要性。还对IgE介导的FcεR上调进行了研究，结果表明，FcεR的配体占据可显著减缓FcεR的降解速率。这种降解涉及细胞表面介导的一个38千道尔顿FcεR片段的释放，该片段可用单克隆抗FcεR抗体分离。因此，这些结果表明，淋巴细胞受体获得显著的IgE结合能力需要翻译后加工；一旦获得这种能力，其降解会因FcεR被配体占据而减缓。至少在啮齿动物模型系统中，这种降解减缓有助于解释在高IgE水平存在时FcεR水平的升高。
