Pernegger G, Schulz T F, Hosp M, Myones B L, Petzer A L, Eigentler A, Böck G, Wick G, Dierich M P
Institute for Hygiene, Innsbruck, Austria.
Immunology. 1988 Oct;65(2):237-41.
CR2, the receptor for the C3d fragment of the third complement component and for Epstein-Barr virus (EBV) has been shown, on mouse B cells, to be involved in the control of B-cell proliferation by acting as a receptor for macrophage-derived growth factors. We examined whether the growth of a Burkitt lymphoma cell line, RAJI, could be influenced by ligands of human CR2. In serum-free culture, purified human C3d, as well as three monoclonal antibodies to distinct epitopes on human CR2, were capable of enhancing the growth rate of RAJI cells two to five-fold. This effect could not be observed if even trace amounts of serum were present in the culture medium. Simultaneous addition of pairs of antibodies did not enhance the growth rate, suggesting that a particular engagement of CR2 may be critical in order to induce a stimulatory effect. These results indicate that in a homologous serum-free human B-cell system human C3d as well as monoclonal antibodies to human CR2 can induce B-cell proliferation and that CR2-mediated triggering of B cells can be induced via epitopes other than the C3d-binding site. In addition we conclude that--unlike normal human B cells--at least some human B-lymphoma cells respond to CR2-mediated stimuli in the absence of any T-cell derived factors. Therefore the control mechanisms exerted through CR2 must still be intact on these autonomously growing cells.
CR2是第三补体成分C3d片段和爱泼斯坦-巴尔病毒（EBV）的受体，在小鼠B细胞上，它已被证明通过作为巨噬细胞衍生生长因子的受体参与B细胞增殖的控制。我们研究了人CR2的配体是否会影响伯基特淋巴瘤细胞系RAJI的生长。在无血清培养中，纯化的人C3d以及针对人CR2上不同表位的三种单克隆抗体，能够使RAJI细胞的生长速率提高2至5倍。如果培养基中存在哪怕痕量的血清，都观察不到这种效应。同时添加成对的抗体不会提高生长速率，这表明CR2的特定结合可能对于诱导刺激效应至关重要。这些结果表明，在同源无血清人B细胞系统中，人C3d以及针对人CR2的单克隆抗体均可诱导B细胞增殖，并且CR2介导的B细胞触发可通过C3d结合位点以外的表位诱导。此外，我们得出结论——与正常人B细胞不同——至少一些人B淋巴瘤细胞在没有任何T细胞衍生因子的情况下对CR2介导的刺激有反应。因此，通过CR2发挥作用的控制机制在这些自主生长的细胞上必定仍然完好无损。
