Vaddi K, Newton R C
Inflammatory Diseases Research, DuPont Merck Pharmaceutical Company, Wilmington, Delaware 19880-0400.
J Leukoc Biol. 1994 Jun;55(6):756-62. doi: 10.1002/jlb.55.6.756.
The biological responses of human monocytes and cells of the monomyelocytic THP-1 cell line to stimulation with members of the beta chemokine family are described in this report. All three chemokines tested, MCP-1, MIP-1 alpha, and RANTES, elicited mobilization of intracellular free calcium in monocytes and THP-1 cells. The magnitude of response was highest with MCP-1 stimulation. MCP-1 desensitized monocyte responses to MIP-1 alpha and RANTES, but no such desensitization was observed in THP-1 cells. MIP-1 alpha or RANTES did not desensitize either monocytes or THP-1 cells to MCP-1 stimulation. All three chemokines elicited a potent chemotactic response in monocytes that was comparable in magnitude to that of f-Met-Leu-Phe. MIP-1 alpha and RANTES required a fivefold higher dose than MCP-1 to elicit a peak response. On the contrary, THP-1 cells showed no significant chemotactic response. Studies of the desensitization of the monocyte chemotactic response indicated that all three chemokines are capable of causing complete homologous desensitization. Heterologous desensitization was observed only when monocytes were treated with MCP-1 followed by MIP-1 alpha or RANTES. Studies of actin polymerization and cell polarization responses of monocytes indicated that these two responses attained peak magnitude after 10 min of stimulation with any of the chemokines. Dose-response kinetics were similar to those of the chemotactic response. THP-1 cells again failed to show either of these two responses. Finally, the activation potential of the chemokines was measured by their ability to induce respiratory burst. A tenfold higher concentration than that causing peak chemotactic response was required to elicit respiratory burst and no heterologous desensitization was noticed. Respiratory burst could be induced in THP-1 cells with a direct protein kinase C activator but not with any of the chemokines. These results indicate that, of the three examples tested, MCP-1 is the most potent member of the beta chemokine family in the biological responses examined. Although a calcium response was elicited in THP-1 cells with chemokines, a lack of subsequent responses indicates some missing links in the downstream signal transduction pathways.
本报告描述了人类单核细胞及单核细胞系THP-1细胞对β趋化因子家族成员刺激的生物学反应。所检测的三种趋化因子，即单核细胞趋化蛋白-1（MCP-1）、巨噬细胞炎性蛋白-1α（MIP-1α）和调节激活正常T细胞表达和分泌因子（RANTES），均可引起单核细胞和THP-1细胞内游离钙的动员。MCP-1刺激引起的反应幅度最高。MCP-1使单核细胞对MIP-1α和RANTES的反应脱敏，但在THP-1细胞中未观察到这种脱敏现象。MIP-1α或RANTES均未使单核细胞或THP-1细胞对MCP-1刺激产生脱敏。所有三种趋化因子均可在单核细胞中引发强烈的趋化反应，其幅度与N-甲酰甲硫氨酰-亮氨酰-苯丙氨酸（f-Met-Leu-Phe）相当。MIP-1α和RANTES引发峰值反应所需的剂量比MCP-1高五倍。相反，THP-1细胞未表现出明显的趋化反应。对单核细胞趋化反应脱敏的研究表明，所有三种趋化因子均能够引起完全的同源脱敏。仅当单核细胞先用MCP-1处理，再用MIP-1α或RANTES处理时，才观察到异源脱敏。对单核细胞肌动蛋白聚合和细胞极化反应的研究表明，在用任何一种趋化因子刺激10分钟后，这两种反应达到峰值幅度。剂量反应动力学与趋化反应相似。THP-1细胞再次未表现出这两种反应中的任何一种。最后，通过趋化因子诱导呼吸爆发的能力来测定其激活潜能。引发呼吸爆发所需的浓度比引起峰值趋化反应的浓度高十倍，且未观察到异源脱敏现象。直接的蛋白激酶C激活剂可在THP-1细胞中诱导呼吸爆发，但任何一种趋化因子均不能。这些结果表明，在所检测的三个例子中，MCP-1是β趋化因子家族在所检测的生物学反应中最有效的成员。尽管趋化因子可在THP-1细胞中引发钙反应，但随后缺乏反应表明下游信号转导途径中存在一些缺失环节。
