美国研究人员最近鉴别出一种在B淋巴细胞分裂、增殖过程中所必需的关键蛋白。科学家说，这项发现将能帮助开发针对多发性骨髓瘤等疾病的新疗法。
大量、快速生成B淋巴细胞等免疫细胞是构建免疫系统的关键。但如果B淋巴细胞的分裂、增殖得不到控制，就可能引发多发性骨髓瘤等疾病；如果B淋巴细胞攻击目标错误，就可能引发自体免疫性疾病。
美国加州大学圣迭戈分校医学院的研究人员8日在《自然·免疫学》杂志网络版上说，他们发现一种名为CD98hc的蛋白可影响B淋巴细胞分裂、增殖，这种蛋白在几乎所有脊椎动物身体中都存在，但科学家一直不清楚它在免疫过程中的作用。
论文第一作者约瑟夫·坎托说，过去人们在静息淋巴细胞过程中发现这种蛋白的含量较低，因此用它做活化标记物。但现在发现，当B淋巴细胞受抗原刺激，比如在阻止细菌入侵机体时，CD98hc蛋白的含量会激增。
进一步的实验发现，缺乏这种蛋白的小鼠对病原体不会产生正常的抗体反应。
坎托说，当缺乏CD98hc蛋白时，B淋巴细胞就不能快速分裂。这表明，CD98hc蛋白在大量增加B淋巴细胞、促发免疫反应过程中发挥着不可缺少的作用。
研究人员推测，人们将来也许可以通过抑制CD98hc蛋白，阻止B淋巴细胞异常增殖或阻止B淋巴细胞发生错误攻击，进而阻止多发性骨髓瘤等疾病的发生。（生物谷Bioon.com）
生物谷推荐原始出处：
Nature Immunology 8 March 2009 | doi:10.1038/ni.1712
CD98hc facilitates B cell proliferation and adaptive humoral immunity
Joseph Cantor1, Cecille D Browne2, Raphael Ruppert3, Chloé C Féral4, Reinhard F?ssler3, Robert C Rickert2 & Mark H Ginsberg1
The proliferation of antigen-specific lymphocytes and resulting clonal expansion are essential for adaptive immunity. We report here that B cell–specific deletion of the heavy chain of CD98 (CD98hc) resulted in lower antibody responses due to total suppression of B cell proliferation and subsequent plasma cell formation. Deletion of CD98hc did not impair early B cell activation but did inhibit later activation of the mitogen-activated protein kinase Erk1/2 and downregulation of the cell cycle inhibitor p27. Reconstitution of CD98hc-deficient B cells with CD98hc mutants showed that the integrin-binding domain of CD98hc was required for B cell proliferation but that the amino acid–transport function of CD98hc was dispensable for this. Thus, CD98hc supports integrin-dependent rapid proliferation of B cells. We propose that the advantage of adaptive immunity favored the appearance of CD98hc in vertebrates.
1 Department of Medicine, University of California San Diego, La Jolla, California, USA.
2 Program of Inflammatory Disease Research, Infectious and Inflammatory Disease Center, Burnham Institute for Medical Research, La Jolla, California, USA.
3 Department of Molecular Medicine, Max Planck Institute of Biochemistry, Martinsried, Germany.
4 Institut National de la Santé et de la Recherche Médicale, Nice-Sophia Antipolis University, Nice, France.
