Sun F, Maercklein P, Fitzpatrick L A
Department of Medicine, Mayo Clinic, Rochester, Minnesota.
J Bone Miner Res. 1994 Jul;9(7):971-6. doi: 10.1002/jbmr.5650090703.
Cell-cell interactions are important in the regulation of endocrine cell secretion. To investigate the possibility that cell communication may alter the regulation of parathyroid cell secretion, we utilized the reverse hemolytic plaque assay (RHPA) to measure parathyroid hormone (PTH) release from individual cells. Bovine parathyroid cells were dispersed and plated with protein A-conjugated erythrocytes at cell densities ranging from 0.9 to 36 x 10(2) cells/cm2 in 0.2 mM calcium. Cell populations were greater than 98% homogenous as determined by immunocytochemistry and in situ hybridization for PTH mRNA. Plaques were developed and data analyzed for the amount of PTH per cell released (plaque area in microns 2 x 10(4)) and the determination of cell recruitment (% plaques formed). A positive correlation existed between parathyroid cell density and the amount of PTH released. As the distance between cells increased, the plaque area (amount of PTH released per cell) decreased (ranging from 1.0 x 10(4) microns 2 at 0.9 x 10(2) cells/cm2 versus 1.6 x 10(4) microns 2 at 36 x 10(2) cells/cm2). The percentage of cells releasing PTH (recruitment) also decreased (16% at 0.9 x 10(2) cells/cm2 versus 47% at 36 x 10(2) cells/cm2). These data suggest that parathyroid cells in close proximity are stimulated to secrete more hormone than those at lesser densities. In addition, parathyroid cells are recruited to secrete PTH when plated at high density. Factor(s) released by the parathyroid cell may increase cell responsiveness and stimulate secretion in a paracrine fashion.
细胞间相互作用在内分泌细胞分泌的调节中很重要。为了研究细胞通讯是否可能改变甲状旁腺细胞分泌的调节，我们利用反向溶血空斑试验（RHPA）来测量单个细胞甲状旁腺激素（PTH）的释放。将牛甲状旁腺细胞分散，并在0.2 mM钙中以0.9至36×10²个细胞/cm²的细胞密度与蛋白A偶联的红细胞一起铺板。通过免疫细胞化学和PTH mRNA的原位杂交确定细胞群体的同质性大于98%。显影空斑并分析每个细胞释放的PTH量（空斑面积，单位为平方微米×10⁴）以及细胞募集情况（形成的空斑百分比）。甲状旁腺细胞密度与释放的PTH量之间存在正相关。随着细胞间距离增加，空斑面积（每个细胞释放的PTH量）减小（在0.9×10²个细胞/cm²时为1.0×10⁴平方微米，而在36×10²个细胞/cm²时为1.6×10⁴平方微米）。释放PTH的细胞百分比（募集）也降低（在0.9×10²个细胞/cm²时为16%，而在36×10²个细胞/cm²时为47%）。这些数据表明，紧密相邻的甲状旁腺细胞比密度较低的细胞受到刺激分泌更多激素。此外，当以高密度铺板时，甲状旁腺细胞被募集来分泌PTH。甲状旁腺细胞释放的因子可能以旁分泌方式增加细胞反应性并刺激分泌。
