McCall E, Bagby G C
Blood. 1985 Mar;65(3):689-95.
Cultured monocytes release a factor, monocyte-derived recruiting activity (MRA), which stimulates fibroblasts, endothelial cells, and T lymphocytes to produce colony-stimulating activity (CSA). We studied the kinetics of MRA production using a technique in which MRA levels were measured in a two stage bioassay. We used umbilical vein endothelial cells as the MRA-responsive (CSA-producing) cells, and normal colony-forming unit granulocyte-macrophage (CFU-GM)-enriched bone marrow cells (T lymphocyte- and monocyte-depleted, low density bone marrow cells) as the CSA-responsive cells. MRA stimulated a 30-fold increase in CSA production by endothelial cells. MRA production was detected in supernatants from as few as 10(3) monocytes per milliliter, required the presence of fetal calf serum, and was inhibited by cycloheximide (10 to 100 micrograms/mL) and puromycin (10 to 50 micrograms/mL). Production was detectable after 24 hours of monocyte incubation, was maintained for three days, and fell to undetectable levels by seven days. With the addition of bacterial endotoxin (lipopolysaccharide [LPS]) (50 micrograms per 10(6) cells), MRA was detectable after only three hours of incubation, and levels peaked at 24 hours. Further, maximum MRA levels in the supernatants of LPS-stimulated monocytes were up to ten times greater than peak levels in the supernatants of unstimulated monocytes. Endotoxin augmented monocyte production of MRA to a greater extent than it did CSA production, indicating that the stimulation of CSA production by endotoxin may be at least partly indirect. The responsiveness of MRA production to endotoxin in vitro is consistent with the notion that MRA may be a biologically relevant regulator of CSA production by cells of the hematopoietic microenvironment.
培养的单核细胞释放一种因子，即单核细胞衍生募集活性（MRA），它可刺激成纤维细胞、内皮细胞和T淋巴细胞产生集落刺激活性（CSA）。我们使用一种在两阶段生物测定中测量MRA水平的技术研究了MRA产生的动力学。我们将脐静脉内皮细胞用作MRA反应性（产生CSA的）细胞，并将正常的富含集落形成单位粒细胞 - 巨噬细胞（CFU - GM）的骨髓细胞（T淋巴细胞和单核细胞耗竭的低密度骨髓细胞）用作CSA反应性细胞。MRA刺激内皮细胞产生的CSA增加了30倍。每毫升低至10³个单核细胞的上清液中即可检测到MRA的产生，这需要胎牛血清的存在，并且受到环己酰亚胺（10至100微克/毫升）和嘌呤霉素（10至50微克/毫升）的抑制。单核细胞孵育24小时后可检测到产生，持续三天，到七天时降至检测不到的水平。加入细菌内毒素（脂多糖[LPS]）（每10⁶个细胞50微克）后，仅孵育三小时即可检测到MRA，且水平在24小时达到峰值。此外，LPS刺激的单核细胞上清液中的最大MRA水平比未刺激的单核细胞上清液中的峰值水平高多达十倍。内毒素增强单核细胞产生MRA的程度大于其增强CSA产生的程度，这表明内毒素对CSA产生的刺激可能至少部分是间接的。MRA产生在体外对内毒素的反应性与MRA可能是造血微环境细胞产生CSA的生物学相关调节因子这一观点一致。
