简述b细胞的特点和主要生物学功能

2024-12-03 01:42:04
推荐回答(1个)
回答1:

B细胞的主要功能是产生抗体介导体液免疫应答。此外,活化的B细胞还可提呈可溶性抗原。
(一)产生抗体介导体液免疫应答
B细胞产生的抗体主要以下列几种方式介导体液免疫应答。
1.中和作用 病毒和胞内细菌必须感染细胞才能复制及生长繁殖,并在细胞间传播。这类病原体是藉与靶细胞表面的特异分子(如受体)结合而感染细胞的。某些针对病原体的抗体,可阻断病原体与靶细胞的结合,抗体的这种作用称为中和作用(neutralization)。抗体的中和作用主要针对病毒和胞内细菌的感染,在中和细菌外毒素作用中也起重要作用。
2.调理作用 抗体与病原体表面结合,其Fc段又可与吞噬细胞表面的Fc受体结合,将病原体带至吞噬细胞处,使之易被吞噬,抗体的这种作用称为抗体的调理作用(opsonization)。此外,抗体与病原体表面结合后,激活补体,并形成抗原-抗体-补体复合物,复合物中的补体成分与吞噬细胞表面的相应补体受体结合,把病原体“带”至吞噬细胞处,使之易被吞噬。
3.参与补体的溶细胞或溶菌作用 IgG和IgM抗体结合细胞或细菌可通过经典途径激活补体,最后形成攻膜复合物(MAC),导致细胞或细菌的溶解。
4.ADCC IgG抗体结合病毒感染细胞或肿瘤细胞后,NK细胞可通过表面的Fc受体与IgG的Fc段结合,从而杀伤靶细胞。

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