Weigle W O
Department of Immunology, Scripps Clinic and Research Foundation, La Jolla, California.
Crit Rev Immunol. 1987;7(4):285-324.
The cellular and biochemical pathways of B-cell activation and the role of antigen presentation by B cells are reviewed. It appears that B cells may be activated by two cellular pathways, one of which is MHC restricted, involving cognate recognition between antigen-presenting B cells and T cells. A second pathway proposed by others is MHC unrestricted and does not involve cognate T/B-cell recognition, with the initial signal to the B cell given by antigen alone. Subsequent to antigen activation, both pathways are driven by nonspecific factors derived from T cells and accessory cells. It is most likely that the MHC-restricted pathway is the major one used in in vivo antibody responses. The pathways used by T-dependent and -independent antigens are also examined. Phospholipid metabolism and Ca2+ mobilization occur following activation of B cells similar to events occurring following activation of other eukaryotic cells. The mechanism and cellular events involved in the induction of antigen-specific immunological tolerance and the possible role of lymphokines in the tolerant state are also discussed. The effects of two extrinsic B-cell activators are presented, one being the Fc fragment of immunoglobulin and its peptides, and the other derivatives of one of the building blocks of nucleic acids. In the former case, small peptides generated from the Fc fragment of immunoglobulin supply differentiating signals to previously activated B cells in the presence of T cells. In the latter case, a family of derivatized guanosine compounds which act both as intracellular mitogens driving B cells to proliferation and immunoglobulin secretion and as potent adjuvants are discussed in detail. These derivatized nucleosides act predominantly on a population of mature B cells which synergize with T-cell lymphokines, and react to a lesser extent with a subpopulation of immature B cells.
本文综述了B细胞活化的细胞和生化途径以及B细胞抗原呈递的作用。B细胞可能通过两种细胞途径被激活，其中一种是MHC限制的，涉及抗原呈递B细胞和T细胞之间的同源识别。其他人提出的第二种途径是MHC非限制的，不涉及同源T/B细胞识别，仅由抗原向B细胞提供初始信号。抗原激活后，这两种途径均由T细胞和辅助细胞衍生的非特异性因子驱动。很可能MHC限制途径是体内抗体应答中使用的主要途径。还研究了T依赖性和T非依赖性抗原所使用的途径。B细胞激活后会发生磷脂代谢和Ca2+动员，这与其他真核细胞激活后发生的事件类似。还讨论了诱导抗原特异性免疫耐受的机制和细胞事件以及淋巴因子在耐受状态下可能发挥的作用。介绍了两种外在B细胞激活剂的作用，一种是免疫球蛋白的Fc片段及其肽段，另一种是核酸组成成分之一的衍生物。在前一种情况下，免疫球蛋白Fc片段产生的小肽在T细胞存在时为先前激活的B细胞提供分化信号。在后一种情况下，详细讨论了一类衍生化的鸟苷化合物，它们既作为驱动B细胞增殖和免疫球蛋白分泌的细胞内有丝分裂原，又作为强效佐剂。这些衍生化核苷主要作用于与T细胞淋巴因子协同作用的成熟B细胞群体，对未成熟B细胞亚群的反应程度较小。
