Goldstein H, Koerholz D, Chesky L, Fan X D, Ambrus J L
Department of Pediatrics, Albert Einstein College of Medicine, Bronx, NY 10463.
J Immunol. 1990 Aug 1;145(3):952-61.
Lymphokines including IL-2, IL-4, and IL-6 are involved in the induction of Ig production by activated B cells. We have investigated the role of protein kinases in IL-6-induced IgM secretion by SKW6.4 cells, an IL-6 responsive B cell line. IL-6-stimulated IgM production was inhibited by elevated intracellular cAMP induced either by the addition of dibutyryl cAMP or cholera toxin. The inhibitory effect of elevated intracellular cAMP was blocked by n-(2-(Methylamino)ethyl)-5-isoquinolinesulfonic dihydrochloride (H8), an inhibitor of protein kinase A. H8 did not affect IgM secretion induced by IL-6. In contrast, the addition of 1-(5-isoquinolinesulfonyl)-2-methylpiperizine dihydrochloride (H7), an inhibitor of protein kinase C activity, markedly inhibited IL-6-stimulated IgM production by SKW6.4 cells. H7 and elevated intracellular cAMP inhibited IgM mRNA expression and subsequent IgM synthesis by SKW6.4 cells. SKW6.4 proliferation, as determined by [3H]thymidine incorporation, was not markedly affected by IL-6, dibutyryl cAMP, cholera toxin, H7 or H8. PMA, an activator of protein kinase C, directly stimulated significant IgM secretion by SKW6.4 cells. When added to PMA-stimulated SKW6.4 cells, IL-6 stimulated additional IgM production. This observation suggested that IL-6 could stimulate differentiation without activating protein kinase C. This was confirmed by demonstrating that IL-6 did not stimulate production of diacylglycerol, did not induce the translocation of protein kinase C from the cytosolic compartment to the plasma membrane and could induce SKW6.4 cells to produce IgM after depletion of their cellular protein kinase C by PMA. Taken together these results suggests that IL-6-stimulated IgM production requires utilization of an H7-inhibitable protein kinase that can be inhibited by a protein kinase A-dependent pathway. Despite the fact that PMA can stimulate IgM production in SKW6.4 cells, IL-6 appears to use a protein kinase pathway other than protein kinase C to induce IgM production.
包括白细胞介素 -2、白细胞介素 -4 和白细胞介素 -6 在内的淋巴因子参与激活的 B 细胞诱导 Ig 产生的过程。我们研究了蛋白激酶在白细胞介素 -6 诱导的 SKW6.4 细胞（一种对白细胞介素 -6 有反应的 B 细胞系）分泌 IgM 中的作用。通过添加二丁酰环磷腺苷或霍乱毒素诱导细胞内 cAMP 升高，可抑制白细胞介素 -6 刺激的 IgM 产生。蛋白激酶 A 的抑制剂 N-(2-(甲氨基)乙基)-5-异喹啉磺酸二盐酸盐（H8）可阻断细胞内 cAMP 升高的抑制作用。H8 不影响白细胞介素 -6 诱导的 IgM 分泌。相反，添加蛋白激酶 C 活性抑制剂 1-(5-异喹啉磺酰基)-2-甲基哌嗪二盐酸盐（H7）可显著抑制白细胞介素 -6 刺激的 SKW6.4 细胞产生 IgM。H7 和细胞内 cAMP 升高抑制了 SKW6.4 细胞中 IgM mRNA 的表达及随后的 IgM 合成。通过 [3H]胸苷掺入法测定，白细胞介素 -6、二丁酰环磷腺苷、霍乱毒素、H7 或 H8 对 SKW6.4 细胞增殖无明显影响。蛋白激酶 C 的激活剂佛波酯（PMA）可直接刺激 SKW6.4 细胞分泌大量 IgM。当添加到 PMA 刺激的 SKW6.4 细胞中时，白细胞介素 -6 可刺激产生更多的 IgM。这一观察结果表明白细胞介素 -6 可在不激活蛋白激酶 C 的情况下刺激分化。这一点通过以下实验得到证实：白细胞介素 -6 不刺激二酰甘油的产生，不诱导蛋白激酶 C 从胞质区室转位到质膜，并且在通过 PMA 耗尽细胞内蛋白激酶 C 后，白细胞介素 -6 仍可诱导 SKW6.4 细胞产生 IgM。综上所述，这些结果表明白细胞介素 -6 刺激的 IgM 产生需要利用一种可被 H7 抑制的蛋白激酶，而该蛋白激酶可被蛋白激酶 A 依赖性途径抑制。尽管 PMA 可刺激 SKW6.4 细胞产生 IgM，但白细胞介素 -6 似乎使用蛋白激酶 C 以外的蛋白激酶途径来诱导 IgM 产生。
