Kaliner M
J Clin Invest. 1977 Oct;60(4):951-9. doi: 10.1172/JCI108850.
The addition of specific antigen to IgE-sensitized human lung tissue causes the secretion of the mediators histamine and slow-reacting substance of anaphylaxis. The mechanisms by which increased levels of cyclic AMP suppress and increased levels of cyclic GMP enhance this secretory process were studied. Colchicine, an agent which disrupts many secretory reactions by binding to microtubules in their disassembled 6S form, was a relatively ineffective inhibitor of the antigen-induced release of mediators unless lung fragments were incubated at 4 degrees C for 60 min to induce microtubular disassembly. As colchicine appeared to inhibit the immunologic secretion of mediators from human lung tissue most effectively after microtubular disassembly, the capacity of colchicine to modulate the release reaction indicated the state of microtubular assembly; inhibition by colchicine signaled a shift to the colchicine-sensitive 6S subunits whereas failure to inhibit suggested maintenance in the colchicine-resistant polymerized state.Exogenously added 8-Bromo-cyclic GMP prevented low temperature-facilitated colchicine suppression of mediator release suggesting that increased levels of cyclic GMP stabilize polymerized microtubules. Transiently increased cyclic AMP concentrations, either exogenously added as 8-Bromo-cyclic AMP or endogenously produced by isoproterenol, promoted colchicine suppression of mediator release suggesting that microtubular disassembly was produced. Direct measurement of cyclic AMP levels revealed parallel kinetics after isoproterenol stimulation between control and colchicine-treated lung fragments. The requirement for functional microtubules in the release reaction may occur after the antigen IgE-stimulated activation of a serine esterase, energy utilization, and an intracellular calcium requirement. The mechanism by which cyclic nucleotides influence microtubular assembly is postulated to involve the degree of phosphorylation-dephosphorylation of microtubules.
向IgE致敏的人肺组织中添加特异性抗原会导致组胺和过敏反应慢反应物质等介质的分泌。研究了环磷酸腺苷（cAMP）水平升高抑制以及环磷酸鸟苷（cGMP）水平升高增强这一分泌过程的机制。秋水仙碱通过与处于解聚6S形式的微管结合来破坏许多分泌反应，它是抗原诱导的介质释放的相对无效抑制剂，除非肺组织碎片在4℃孵育60分钟以诱导微管解聚。由于秋水仙碱似乎在微管解聚后最有效地抑制人肺组织中介质的免疫分泌，秋水仙碱调节释放反应的能力表明了微管组装的状态；秋水仙碱的抑制表明转变为对秋水仙碱敏感的6S亚基，而未能抑制则表明维持在对秋水仙碱耐药的聚合状态。外源性添加的8-溴环磷酸鸟苷可防止低温促进的秋水仙碱对介质释放的抑制，这表明环磷酸鸟苷水平升高可稳定聚合的微管。短暂升高的环磷酸腺苷浓度，无论是作为8-溴环磷酸腺苷外源性添加还是由异丙肾上腺素内源性产生，都促进了秋水仙碱对介质释放的抑制，这表明产生了微管解聚。对环磷酸腺苷水平的直接测量显示，异丙肾上腺素刺激后，对照和秋水仙碱处理的肺组织碎片之间具有平行的动力学。释放反应中对功能性微管的需求可能发生在抗原IgE刺激丝氨酸酯酶激活、能量利用和细胞内钙需求之后。推测环核苷酸影响微管组装的机制涉及微管的磷酸化-去磷酸化程度。
