Oliver A M, Martin F, Kearney J F
Division of Developmental and Clinical Immunology, Department of Microbiology, University of Alabama, Birmingham 35294, USA.
J Immunol. 1999 Jun 15;162(12):7198-207.
Ag encounter will recruit Ag-specific cells from the pool of mature B lymphocytes in the spleen and activate them to perform effector functions: generation of Ab-forming cells (plasma cells) and presentation of Ag to T cells. We have compared the ability of mature follicular and marginal zone cells to develop into effector B cells. The generation of marginal zone B cells and their localization in the marginal sinus area are T cell and CD40 ligand independent, suggesting that they do not represent a postgerminal center population. Compared with mature recirculating follicular B cells, they express several characteristics of previous antigenic experience, including higher levels of B7.1 (CD80) and B7.2 (CD86) when freshly isolated and following in vitro stimulation. After a brief 6- to 8-h in vitro stimulation with LPS or anti-CD40 Abs, marginal zone B cells become potent APCs. In addition, their ability to proliferate and differentiate into plasma cells in response to low doses of T-independent polyclonal stimuli (LPS) is far greater than that of follicular B cells. These findings indicate a functional heterogeneity within splenic mature B lymphocytes, with marginal zone B cells having the capacity to generate effector cells in early stages of the immune response against particulate Ags scavenged efficiently in this special anatomical site.
抗原接触会从脾脏中成熟B淋巴细胞库中募集抗原特异性细胞，并激活它们执行效应功能：产生抗体形成细胞（浆细胞）并将抗原呈递给T细胞。我们比较了成熟滤泡细胞和边缘区细胞发育为效应B细胞的能力。边缘区B细胞的产生及其在边缘窦区域的定位不依赖于T细胞和CD40配体，这表明它们不代表生发中心后群体。与成熟的循环滤泡B细胞相比，它们表现出一些先前抗原经历的特征，包括刚分离时以及体外刺激后更高水平的B7.1（CD80）和B7.2（CD86）。在用LPS或抗CD40抗体进行短暂的6至8小时体外刺激后，边缘区B细胞成为有效的抗原呈递细胞。此外，它们在响应低剂量非T细胞依赖性多克隆刺激（LPS）时增殖并分化为浆细胞的能力远大于滤泡B细胞。这些发现表明脾脏成熟B淋巴细胞内存在功能异质性，边缘区B细胞有能力在针对在此特殊解剖部位有效清除的颗粒性抗原的免疫反应早期阶段产生效应细胞。
