Birkenmaier C, Hong Y S, Horn J K
Department of Surgery, San Francisco General Hospital, University of California 64143-0807.
J Trauma. 1992 Apr;32(4):473-8; discussion 478-9.
The monocyte is a pivotal cell in septic patients that responds to endotoxin with release of inflammatory cytokines. Monocytes display on their surface a receptor (CD14) for complexes formed by endotoxin (lipopolysaccharide, LPS) and a plasma LPS-binding protein (LBP). We compared monocytes obtained from normal controls with those obtained from septic patients for expression of CD14 by flow cytometric analysis of immunofluorescent-stained cells. In normal individuals and patients, 75%-95% of monocytes are CD14 positive (CD14+). Mean fluorescence exhibited by the CD14+ population was measured after maintaining cells at 37 degrees C for 15 minutes and compared with baseline cells held at 4 degrees C (mean fluorescence ratio). All cells increased their CD14 mean fluorescence ratio with warming; however, the level achieved by monocytes obtained from septic patients was on average 78% +/- 8% of control levels (p = 0.014). To further clarify CD14 expression, we examined the effect of Escherichia coli LPS on normal monocytes by comparing monocytes treated in serum-free buffer (no LBP) with monocytes treated in whole blood (containing LBP). The LPS (1.0 ng/mL) incubated with whole blood for 120 minutes generated an increase in CD14+ mean fluorescence compared with buffer. In contrast, phorbol myristate acetate lowered CD14+ mean fluorescence levels. These data indicate that normal monocytes incubated in the presence of ligand (LBP-LPS complexes) increase their expression of CD14, whereas CD14 expression in septic patients is diminished. We conclude that monocytes from septic patients were responsive to other stimuli aside from LPS and that decreased expression of CD14 may indicate a poor prognosis.
单核细胞是脓毒症患者体内的关键细胞，可通过释放炎性细胞因子对内毒素作出反应。单核细胞表面存在一种受体（CD14），可识别由内毒素（脂多糖，LPS）与血浆LPS结合蛋白（LBP）形成的复合物。我们通过对免疫荧光染色细胞进行流式细胞术分析，比较了正常对照者与脓毒症患者的单核细胞中CD14的表达情况。在正常个体和患者中，75%-95%的单核细胞为CD14阳性（CD14+）。将细胞在37℃孵育15分钟后，测量CD14+群体的平均荧光强度，并与保存在4℃的基线细胞进行比较（平均荧光比率）。所有细胞在升温后其CD14平均荧光比率均升高；然而，脓毒症患者的单核细胞达到的水平平均为对照水平的78%±8%（p = 0.014）。为进一步阐明CD14的表达情况，我们通过比较无血清缓冲液（不含LBP）处理的单核细胞与全血（含LBP）处理的单核细胞，研究了大肠杆菌LPS对正常单核细胞的影响。与缓冲液相比，LPS（1.0 ng/mL）与全血孵育120分钟后，CD14+平均荧光强度增加。相反，佛波酯肉豆蔻酸酯降低了CD14+平均荧光水平。这些数据表明，在配体（LBP-LPS复合物）存在的情况下孵育的正常单核细胞会增加其CD14的表达，而脓毒症患者的CD14表达则降低。我们得出结论，脓毒症患者的单核细胞除了对LPS有反应外，还对其他刺激有反应，CD14表达降低可能预示预后不良。
