重组白介素6-假单胞菌外毒素融合蛋白对正常BN大鼠骨髓粒系造血的作用

本文报道了重组白介素6-假单胞菌外毒素融合蛋白(IL-6-PE40)对正常BN大鼠骨髓粒系造血的体外效应。10ng/ml的IL-6-PE40对高表达IL-6受体的U266骨髓瘤细胞的蛋白质合成抑制率为50％,1000ng/ml则为100％。1～1000ng/mlIL-6-PE40对正常骨髓未纯化细胞的CFU-GM集落形成和DNA合成无明显抑制,但IL-6却具有一定的刺激效应。提示正常骨髓粒系祖细胞和骨髓细胞可能不表达IL-6受体,IL-6-PE40对粒系造血仍具有某些细胞毒作用,但被IL-6-PE40中的IL-6极大地削弱了。

EFFECT OF RECOMBINANT INTERLEUKIN-6-PSEUDO- MONAS EXOTOXIN CHIMERIC PROTEIN (IL-6-PE40) ON IN VITRO GRANULOPOIESIS OF NORMAL BN RAT

The fusion protein of IL-6-PE40 which is composed of human interleukin 6 fused with mutant form of pseudomonas exotoxin (PE) devoid of its native cell recognition domain can kill tumor cells expressing high levels of IL-6 receptors. In the present study cytotoxic effect of IL-6-PE40 on granulopoiesis of bone marrow in normal BN rat was assessed and compared with effect of human IL-6 using granulocyte-macrophage colony forming unit (CFU-GM) and 3H-TdR incorporation assays. The fused protein of IL-6-PE40 is cytotoxic to U266, a human myeloma cell line expressing high levels of IL-6 receptors on the cell surface. The dose of IL-6-PE40 required to inhibit protein synthesis by 50% was 10ng/ml, while 1000ng/ml of IL-6-PE40 produced 100% inhibition of protein synthesis. In contrast, there was no obvious cytotoxic effect on CFU-GM growth and DNA synthesis in normal bone marrow at the dose range of 1-1000ng/ml of IL-6-PE40. On the other hand, rhIL-6 itself at a dose range of 1000U / ml to 4000U / ml was able to support moderately CFU-GM growth and DNA synthesis. These findings provide evidence that granulocyte-macrophage hematopoietic progenitors and bone marrow cells do not express IL-6 receptors on their surface and are not sensitive to IL-6-PE40 in vitro.