Lewis G K, Ranken R, Nitecki D E, Goodman J W
J Exp Med. 1976 Aug 1;144(2):382-97. doi: 10.1084/jem.144.2.382.
Strain A/J mice made secondary indirect plaque-forming cell (PFC) responses to azobenzenearsonate (ABA) conjugates of giant keyhole limpet hemocyanin (KLH), a thymic-dependent antigen, but not to conjugates of Ficoll, a T-independent antigen. ABA-Ficoll was also unable to elicit a response in animals primed with ABA-KLH, which have an expanded anti-ABA memory cell pool. On the other hand, ABA-Ficoll rendered mice unresponsive to ABA-KLH when administered before priming or boosting with the T-dependent immunogen. Hence, the T-independent antigen was able to tolerize but unable to trigger B-memory cells responsive to the T-dependent antigen. A/J mice immunized with dinitrophenyl conjugates of Ficoll or bovine IgG (BGG) made vigorous IgM and IgG PFC responses. PFC responses to ABA-KLH and 2,4-dinitrophenyl (DNP)-BGG were abrogated by depleting mice of C3 with cobra venom factor, whereas the IgM and IgG PFC responses to DNP-Ficoll were unaffected. B lymphocytes were fractionated on the basis of receptors for C3 and the subpopulations were assayed for in vitro PFC responses to DNP-Ficoll. Very little response was obtained from complement receptor lymphocyte [CRL(+)] B cells, whereas CRL(-) cells were more responsive than unfractionated B cells. Both populations responded to a polyclonal B-cell mitogen (lipopolysaccharide). On the other hand, the in vitro PFC response to a T-dependent antigen (sheep erythrocytes) correlated with the presence of CRL(+) B cells in the cultures. However, a minor component of this response, sensitive to anti-Thy-1 serum, was made by CRL(-) B cells, indicating the existence of subpopulations of T-dependent B cells with different signalling requirements. The results suggest that most B cells responsive to T-dependent antigens possess receptors for C3 and that C3 plays an obligatory role in the response of these cells. A distinct subpopulation of B cells which lack C3 receptors respond to T-independent antigens. The precursors of PFC for the ABA epitope reside largely or exclusively in the CRL(+) compartment in A/J mice, whereas precursors for the DNP determinant are found in both compartments.
A/J品系小鼠对胸腺依赖性抗原巨帽贝血蓝蛋白（KLH）的偶氮苯砷酸盐（ABA）缀合物产生二次间接空斑形成细胞（PFC）反应，但对非胸腺依赖性抗原Ficoll的缀合物无反应。ABA-Ficoll也无法在以ABA-KLH免疫的动物中引发反应，这些动物具有扩大的抗ABA记忆细胞库。另一方面，在以胸腺依赖性免疫原进行初次免疫或加强免疫之前给予ABA-Ficoll时，它会使小鼠对ABA-KLH无反应。因此，非胸腺依赖性抗原能够诱导耐受，但无法触发对胸腺依赖性抗原产生反应的B记忆细胞。用Ficoll或牛IgG（BGG）的二硝基苯基缀合物免疫的A/J小鼠产生强烈的IgM和IgG PFC反应。用眼镜蛇毒因子耗尽小鼠的C3可消除对ABA-KLH和2,4-二硝基苯基（DNP）-BGG的PFC反应，而对DNP-Ficoll的IgM和IgG PFC反应不受影响。根据C3受体对B淋巴细胞进行分离，并检测各亚群对DNP-Ficoll的体外PFC反应。补体受体淋巴细胞[CRL(+)]B细胞几乎没有反应，而CRL(-)细胞比未分离的B细胞反应性更强。两个群体均对多克隆B细胞有丝分裂原（脂多糖）产生反应。另一方面，对胸腺依赖性抗原（绵羊红细胞）的体外PFC反应与培养物中CRL(+)B细胞的存在相关。然而，该反应中对抗Thy-1血清敏感的一小部分是由CRL(-)B细胞产生的，这表明存在具有不同信号需求的胸腺依赖性B细胞亚群。结果表明，大多数对胸腺依赖性抗原产生反应的B细胞具有C3受体，并且C3在这些细胞的反应中起必不可少的作用。一个缺乏C3受体的独特B细胞亚群对非胸腺依赖性抗原产生反应。在A/J小鼠中，ABA表位的PFC前体主要或完全存在于CRL(+)区室中，而DNP决定簇的前体在两个区室中均有发现。
