Analysis of MHC class II presentation of particulate antigens of B lymphocytes.
Analysis of MHC class II presentation of particulate antigens of B lymphocytes.
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DOI：
10.4049/jimmunol.156.8.2809
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发表时间：
1996-04
影响因子：
4.4
通讯作者：
L. Vidard;M. Kovacsovics-Bankowski;S. Kraeft;L. Chen;B. Benacerraf;K. Rock
中科院分区：
文献类型：
--
作者：
L. Vidard;M. Kovacsovics-Bankowski;S. Kraeft;L. Chen;B. Benacerraf;K. Rock
为了产生对大多数蛋白质Ag的Ab应答，B细胞必须首先降解内吞区室中的蛋白质，然后展示与MHC II类分子结合的抗原肽。辅助性T淋巴细胞识别这些复合物并刺激B细胞合成Ab。尽管Ab在宿主防御细菌中起关键作用，但据信B细胞不能内化颗粒状Ag。然而，我们发现B类淋巴母细胞系和LPS激活的B淋巴细胞可以比可溶性Ag更有效地呈递颗粒状Ag高达10（5）倍。此外，当颗粒状Ag与表面IG结合时，它们被未刺激的B细胞有效地呈递。与B细胞相比，巨噬细胞通常以10至1000倍的效率呈递颗粒状Ag，并且还可以呈递来自更宽尺寸范围的颗粒的Ag。我们通过超微结构和免疫荧光分析证明B淋巴母细胞样细胞系结合并内化这些颗粒。细胞松弛素B抑制颗粒Ag的内化和呈递。与此相反，正常淋巴细胞的类似形态学分析表明，虽然银珠结合到细胞表面，它们很少被内化。这些结果提示B细胞对颗粒状Ag的呈递可能存在表面和细胞内两种途径。有趣的是，对于巨噬细胞和B细胞，从颗粒和可溶性Ag产生的表位在定量或定性上不相同，表明这些形式的Ag如何加工和呈递存在差异。
To generate Ab responses to most protein Ags, B cells must first degrade proteins in endocytic compartments and then display antigenic peptides bound to MHC class II molecules. T helper lymphocytes recognize these complexes and stimulate the B cell to synthesize Ab. Although Ab play a key role in host defense against bacteria, it is believed that B cells are incapable of internalizing particulate Ags. However, we find that B lymphoblastoid cell lines and LPS-activated B lymphocytes can present particulate Ag up to 10(5)-fold more efficiently compared with soluble Ag. Moreover, particulate Ags are presented efficiently by unstimulated B cells when they bind to surface Ig. In comparison to B cells, macrophages in general presented particulate Ags 10- to 1000-fold more efficiently and could also present Ag from particles of a much wider range of sizes. We document by ultrastructural and immunofluorescence analysis that B lymphoblastoid cell lines bind and internalize these particles. The internalization and presentation of the particulate Ag is inhibited by cytochalasin B. In contrast, a similar morphologic analysis of normal lymphocytes demonstrated that while Ag beads are bound to the cell surface, they are internalized only rarely. These results suggest there may be both surface and intracellular pathways for the presentation of particulate Ags by B cells. Interestingly, for both macrophages and B cells, the epitopes generated from particulate and soluble Ags were not identical quantitatively or qualitatively, indicating that there are differences in how these forms of Ag are processed and presented.