Petrasch S G, Kosco M H, Perez-Alvarez C J, Schmitz J, Brittinger G
Department of Medicine, University of Essen, Germany.
Immunobiology. 1991 Nov;183(5):451-62. doi: 10.1016/S0171-2985(11)80528-0.
In secondary lymphoid organs, follicular dendritic cells (FDC) are located within B cell follicles and germinal centers. Through their cytoplasmic extensions they come into contact with a large number of neighboring lymphocytes. Using an enzyme cocktail to digest human tonsils followed by ultracentrifugation on bovine serum albumin gradients, single cell suspensions were obtained. Immunocytochemistry revealed that 7% of the cells were FDC, 5% T cells, and 5% macrophages. The remaining population were B cells with greater than 95% being of the germinal center phenotype (i.e. CD19-positive, CD39/sIgD negative). After 24 h of culture up to 44% of the lymphocytes were found in clusters centered around FDC. At the start of the culture as well as 24 and 72 h later, between 31 and 55% of the B cells within FDC associated clusters were in late G1 to M phase of the cell cycle. In contrast, less than 10% of the B cells not in contact with FDC (i.e. outside the clusters) were in an activated state. Autoradiography revealed that after three days of incubation the rate of proliferation was 26.2 times higher for the lymphocytes involved in cluster formation as compared to those cells not associated with FDC. Furthermore, the number of viable B cells after a 72 h mitogen-free culture period was determined. By adding FDC to these preparations, 31.9% of the lymphocytes were rescued from dying. These data show that FDC provide a microenvironment which can maintain the viability, activation and proliferation of germinal center B cells in vitro.
在次级淋巴器官中，滤泡树突状细胞（FDC）位于B细胞滤泡和生发中心内。通过其细胞质延伸部分，它们与大量相邻淋巴细胞接触。使用酶混合物消化人扁桃体，然后在牛血清白蛋白梯度上进行超速离心，获得单细胞悬液。免疫细胞化学显示，7%的细胞为FDC，5%为T细胞，5%为巨噬细胞。其余细胞群体为B细胞，其中超过95%为生发中心表型（即CD19阳性，CD39/sIgD阴性）。培养24小时后，高达44%的淋巴细胞聚集在以FDC为中心的簇中。在培养开始时以及24小时和72小时后，FDC相关簇内31%至55%的B细胞处于细胞周期的G1晚期至M期。相比之下，未与FDC接触的B细胞（即簇外）中，处于活化状态的不到10%。放射自显影显示，孵育三天后，参与簇形成的淋巴细胞的增殖率比未与FDC相关的细胞高26.2倍。此外，还测定了无丝裂原培养72小时后存活B细胞的数量。通过向这些制剂中添加FDC，31.9%的淋巴细胞免于死亡。这些数据表明，FDC提供了一种微环境，可在体外维持生发中心B细胞的活力、活化和增殖。
