Emmrich F, Schilling B, Eichmann K
J Exp Med. 1985 Mar 1;161(3):547-62. doi: 10.1084/jem.161.3.547.
The immune response to the group-specific carbohydrate of group A streptococci (A-CHO) provides an informative in vitro model for the investigation of several aspects of human anticarbohydrate immune responses. A-CHO-specific B cells can be polyclonally activated by pokeweed mitogen (PWM), and, specifically, by in vitro immunization with streptococcal vaccine. High levels of A-CHO-specific antibodies, mainly directed to the immunodominant side chain N-acetyl-D-glucosamine (GlcNAc), occur in healthy adult individuals. Serum antibody levels are reflected in high frequencies of precursor B cells among peripheral blood lymphocytes. In one particular case, greater than 15% of all B cells activated by PWM for IgM production were found to produce IgM anti-A-CHO antibodies, as determined in limiting dilution experiments, as well as by analyzing Ig concentrations in bulk culture experiments. The case with the lowest proportion observed had 0.3% A-CHO-specific B cells among IgM-producing B cells. Preferential PWM activation of anti-A-CHO-producing B cells could be excluded. The comparison of the proportions of anti-A-CHO IgM produced in vivo, and of B cells producing antibodies of this specificity in peripheral blood, suggests a similar distribution of specific precursor B cells in the antibody-producing lymphoid tissue compartments and in peripheral blood. However, nearly all specific antibodies produced in vitro belong to the IgM isotype, whereas IgG anti-A-CHO in high amounts, mostly exceeding the specific IgM, was found only among anti-A-CHO antibodies produced in vivo. Low anti-A-CHO IgG production was seen in polyclonally activated as well as in antigen-activated cultures, whereas, in contrast, total IgG was produced in considerable amounts after polyclonal activation. This suggests a different distribution pattern, and/or diverse differentiation requirements for anti-A-CHO-producing B cells, compared with other B cell species.
对A组链球菌的群特异性碳水化合物（A-CHO）的免疫反应为研究人类抗碳水化合物免疫反应的多个方面提供了一个有益的体外模型。A-CHO特异性B细胞可被商陆有丝分裂原（PWM）多克隆激活，特别是通过用链球菌疫苗进行体外免疫激活。健康成年个体中存在高水平的A-CHO特异性抗体，主要针对免疫显性侧链N-乙酰-D-葡萄糖胺（GlcNAc）。血清抗体水平反映在外周血淋巴细胞中前体B细胞的高频率上。在一个特定案例中，通过有限稀释实验以及分析大量培养实验中的Ig浓度确定，由PWM激活产生IgM的所有B细胞中，超过15%被发现产生IgM抗A-CHO抗体。观察到的比例最低的案例中，产生IgM的B细胞中有0.3%是A-CHO特异性B细胞。可以排除抗A-CHO产生B细胞的优先PWM激活。体内产生的抗A-CHO IgM比例与外周血中产生这种特异性抗体的B细胞比例的比较表明，特异性前体B细胞在产生抗体的淋巴组织区室和外周血中的分布相似。然而，几乎所有体外产生的特异性抗体都属于IgM同种型，而大量的IgG抗A-CHO，大多超过特异性IgM，仅在体内产生的抗A-CHO抗体中发现。在多克隆激活以及抗原激活的培养物中都观察到低水平的抗A-CHO IgG产生，而相比之下，多克隆激活后会产生大量的总IgG。这表明与其他B细胞种类相比，抗A-CHO产生B细胞的分布模式不同和/或分化要求不同。
