Berger M, Birx D L, Wetzler E M, O'Shea J J, Brown E J, Cross A S
J Immunol. 1985 Aug;135(2):1342-8.
It has recently been shown that human neutrophils rapidly increase surface expression of membrane receptors for C3b (CR1) and C3bi (CR3) in response to chemoattractants and other stimuli. In the present studies, we used monoclonal antibodies and flow cytometry to assess the role of Ca2+ in this process. Stimulation with ionophore A23187 in the presence of 1.2 mM Ca2+ increased CR1 330% and CR3 650% compared with unstimulated cells at 37 degrees C. Because this indicated that increasing the cytosolic free Ca2+ caused increased receptor expression, we examined the role of Ca2+ in the response to other stimuli as well. Adding 1.2 mM Ca2+ or 5 mM EDTA to the media in which the polymorphonuclear leukocytes were suspended had no effect on the CR1 response to f-MLP or LTB4, whereas Ca2+ slightly enhanced and EDTA markedly inhibited the CR3 response to these stimuli. The effects of Mg2+-EGTA and EDTA were identical. TMB-8 (200 microM), which inhibits the release of Ca2+ from intracellular stores, completely blocked the increased expression of both receptors induced by fMLP or LTB4. Increased expression of both receptors was also prevented by the calmodulin antagonists chlorpromazine (50 microM) and trifluoperazine (10 microM), but not by chlorpromazine sulfoxide. Phorbol myristate acetate (0.1 ng/ml) increased CR1 230% and CR3 265%. Again Ca2+ and EDTA did not alter the CR1 response, whereas Ca2+ increased CR3 to 287% and EDTA reduced CR3 to 187% of control. TMB-8 (250 microM) completely blocked both CR1 and CR3 responses to this stimulus as well. Thus, release of intracellular Ca2+ is necessary and sufficient for increased CR1 expression in response to diverse stimuli, but maximal increases in CR3 expression require an additional influx of extracellular Ca2+. These results indicate that the mechanisms by which the surface expression of the two different complement receptors increase are different in their requirements for extracellular Ca2+. In comparison with the work of others, we suggest that the processes of increased complement receptor expression and secretion of granular enzymes may also differ.
最近研究表明，人类中性粒细胞在受到趋化因子和其他刺激时，会迅速增加C3b膜受体（CR1）和C3bi膜受体（CR3）的表面表达。在本研究中，我们使用单克隆抗体和流式细胞术来评估Ca2+在此过程中的作用。在37℃下，在1.2 mM Ca2+存在的情况下用离子载体A23187刺激，与未刺激的细胞相比，CR1增加了330%，CR3增加了650%。因为这表明增加胞质游离Ca2+会导致受体表达增加，所以我们也研究了Ca2+在对其他刺激的反应中的作用。向悬浮有多形核白细胞的培养基中添加1.2 mM Ca2+或5 mM EDTA对CR1对f-MLP或LTB4的反应没有影响，而Ca2+略微增强而EDTA显著抑制CR3对这些刺激的反应。Mg2+-EGTA和EDTA的作用相同。抑制细胞内Ca2+释放的TMB-8（200 microM）完全阻断了fMLP或LTB4诱导的两种受体表达的增加。钙调蛋白拮抗剂氯丙嗪（50 microM）和三氟拉嗪（10 microM）也能阻止两种受体表达的增加，但氯丙嗪亚砜则不能。佛波酯肉豆蔻酸酯（0.1 ng/ml）使CR1增加了230%，CR3增加了265%。同样，Ca2+和EDTA没有改变CR1的反应，而Ca2+使CR3增加到对照的287%，EDTA使CR3降低到对照的187%。TMB-8（250 microM）也完全阻断了两种受体对这种刺激的反应。因此，细胞内Ca2+的释放对于响应多种刺激增加CR1表达是必要且充分的，但CR3表达的最大增加需要额外的细胞外Ca2+内流。这些结果表明，两种不同补体受体表面表达增加的机制对细胞外Ca2+的需求不同。与其他人的工作相比，我们认为补体受体表达增加和颗粒酶分泌的过程可能也不同。
