De Groot C, Braun J, Mevissen M L, Wormmeester J
Cellular Immunology Group, University of Amsterdam, The Netherlands.
Lymphokine Res. 1990 Fall;9(3):321-32.
Human tonsillar B lymphocytes proliferate in vitro after activation with immobilized anti-IgM antibodies in combination with interleukin 2 (IL-2) or interleukin 4 (IL-4). In addition to its proliferative effects, IL-4 is also able to inhibit B cell proliferation. An explanation for these different actions of the same protein is not as yet available. The susceptibility to the inhibitory action of IL-4 emerges at late time points after in vitro activation of the B cells, whereas IL-4 shows its growth promoting action during early stages of culture, indicating that activated IL-2 responsive B cells are the targets for IL-4 dependent inhibition. Freshly isolated tonsillar B lymphocytes also appear to be susceptible to IL-4 dependent suppression. Isotonic Percoll gradient centrifugation, that has been used by several groups as a standard procedure to isolate high density, resting used by several groups as a standard procedure to isolate high density, resting cells from tonsil B lymphocytes, does not result in separation of B cells with different in vitro proliferative response to IL-2 and IL-4. However, partial separation of cells with "resting" and "activated" phenotypes can be achieved by centrifugation in slightly hypotonic Percoll gradients. High-density fractions contain cells with a "resting" phenotype which after in vitro activation proliferate with IL-4 but not with IL-2. "Activated" B cells accumulate in the low-density fractions as concluded from the increased expression of transferrin receptors and HLA-DR molecules on these cells. However, these cells no longer proliferate in vitro with immobilized anti-IgM antibodies, possibly due to damage caused by the hypotonic treatment during centrifugation. Our data indicate that resting B cells when activated in vitro with immobilized anti-IgM antibodies proliferate primarily with IL-4 but not with IL-2. In contrast, about 15 hours after activation the cells become responsive to IL-2. At that stage, IL-4 becomes an inhibitory factor.
人扁桃体B淋巴细胞在用固定化抗IgM抗体联合白细胞介素2（IL-2）或白细胞介素4（IL-4）激活后可在体外增殖。除了其增殖作用外，IL-4还能够抑制B细胞增殖。对于同一蛋白质的这些不同作用，目前尚无解释。对IL-4抑制作用的敏感性在B细胞体外激活后的较晚时间点出现，而IL-4在培养早期显示其促生长作用，这表明活化的IL-2反应性B细胞是IL-4依赖性抑制的靶细胞。新鲜分离的扁桃体B淋巴细胞似乎也易受IL-4依赖性抑制。等渗Percoll梯度离心法已被多个研究小组用作从扁桃体B淋巴细胞中分离高密度静息细胞的标准方法，但该方法并不能分离出对IL-2和IL-4具有不同体外增殖反应的B细胞。然而，通过在轻度低渗Percoll梯度中离心可实现具有“静息”和“活化”表型的细胞的部分分离。高密度组分包含具有“静息”表型的细胞，这些细胞在体外激活后与IL-4一起增殖，但不与IL-2一起增殖。从这些细胞上转铁蛋白受体和HLA-DR分子表达增加可推断，“活化”B细胞聚集在低密度组分中。然而，这些细胞在用固定化抗IgM抗体进行体外培养时不再增殖，这可能是由于离心过程中低渗处理造成的损伤。我们的数据表明，用固定化抗IgM抗体在体外激活的静息B细胞主要与IL-4一起增殖，而不与IL-2一起增殖。相反，激活后约15小时，细胞开始对IL-2产生反应。在那个阶段，IL-4成为一种抑制因子。
