Hirani S, Fair D S, Papin R A, Sundsmo J S
Cell Immunol. 1985 May;92(2):235-46. doi: 10.1016/0008-8749(85)90005-x.
It has been previously shown that the activated form of Factor B (Factor Bb) of the alternative pathway of complement activation stimulates monocyte spreading and killing of xenogenic erythrocytes and staphylococci. Factor Bb also stimulates lymphocyte blastogenesis in vitro, and native (uncleaved) Factor B is a major constitutive product of murine macrophages. To evaluate the possible "monokine" or "lymphokine"-like properties of Factor Bb, a radioimmunoassay was developed to measure the quantities of Factor B in phytohemagglutinin (PHA)-mitogen-stimulated cultures of human peripheral blood mononuclear cells. Nonstimulated mononuclear cell cultures from human peripheral blood (containing 10-14% monocytes and greater than 85% lymphocytes) at a density of 3 X 10(6) cells/ml (in serum-free medium) released less than 7 X 10(-10) M/liter (60 ng/ml) of Factor B antigen in 24 hr at 37 degrees C, and when mononuclear cells were stimulated with PHA mitogen in serum-free medium, the levels of Factor B antigen in media at 24 hr were significantly higher 1-3 X 10(-8) M/liter (0.9-2.8 micrograms/ml). The molecular size of Factor B in these media was 50-65 kDa by immunoprecipitation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, a size appropriate for Factor Bb (60 kDa). Since pathological effects of macrophages in autoimmune disease may result from the release of lysosomal hydrolases, the effects of purified Factor Bb on mononuclear phagocytes were investigated in an in vitro system of murine peritoneal exudate macrophages. Factor Bb induced secretion of marker lysosomal hydrolases N-acetyl-beta-D-glucosaminidase (hexosaminidase) and beta-glucuronidase from thioglycollate-elicited murine peritoneal exudate macrophages in a dose-response and kinetic manner. Hydrolase release was induced in serum-free medium without a known particulate activator at a concentration of 80-200 nM (5-13 micrograms/ml) Factor Bb. Maximal release occurred in 3-5 hr at 37 degrees C and extracellular enzyme activity of hexosaminidase and glucuronidase increased as intracellular enzyme levels decreased, suggesting that Factor Bb triggers release of these enzymes from intracellular lysosomal pools. These results provide an example of a complement protein which is synthesized, released, and activated during mononuclear cell culture and which induces release of lysosomal enzymes from macrophages. In conventional terminology, Factor B or Factor Bb might be termed a "lymphokine," "monokine," or "interleukin".
先前的研究表明，补体激活替代途径中的B因子激活形式（B因子b）可刺激单核细胞铺展并杀死异种红细胞和葡萄球菌。B因子b还能在体外刺激淋巴细胞增殖，而天然（未裂解）的B因子是小鼠巨噬细胞的主要组成产物。为了评估B因子b可能具有的“单核因子”或“淋巴因子”样特性，开发了一种放射免疫测定法来测量植物血凝素（PHA）促有丝分裂原刺激的人外周血单核细胞培养物中B因子的量。来自人外周血的未刺激单核细胞培养物（含10 - 14%单核细胞和超过85%淋巴细胞），密度为3×10⁶个细胞/毫升（在无血清培养基中），在37℃下24小时释放的B因子抗原低于7×10⁻¹⁰摩尔/升（60纳克/毫升），当在无血清培养基中用PHA促有丝分裂原刺激单核细胞时，24小时培养基中B因子抗原水平显著升高，为1 - 3×10⁻⁸摩尔/升（0.9 - 2.8微克/毫升）。通过免疫沉淀和十二烷基硫酸钠 - 聚丙烯酰胺凝胶电泳测定，这些培养基中B因子的分子大小为50 - 65千道尔顿，这一大小与B因子b（60千道尔顿）相符。由于自身免疫性疾病中巨噬细胞的病理作用可能源于溶酶体水解酶的释放，因此在小鼠腹腔渗出巨噬细胞的体外系统中研究了纯化的B因子b对单核吞噬细胞的影响。B因子b以剂量反应和动力学方式诱导硫乙醇酸盐诱导的小鼠腹腔渗出巨噬细胞分泌标志性溶酶体水解酶N - 乙酰-β - D - 氨基葡萄糖苷酶（己糖胺酶）和β - 葡萄糖醛酸酶。在无已知颗粒激活剂的无血清培养基中，浓度为80 - 200纳摩尔（5 - 13微克/毫升）的B因子b可诱导水解酶释放。在37℃下3 - 5小时出现最大释放，随着细胞内酶水平降低，己糖胺酶和葡萄糖醛酸酶的细胞外酶活性增加，这表明B因子b触发了这些酶从细胞内溶酶体库中的释放。这些结果提供了一个补体蛋白的例子，该蛋白在单核细胞培养过程中合成、释放并被激活，且能诱导巨噬细胞释放溶酶体酶。按照传统术语，B因子或B因子b可能被称为“淋巴因子”、“单核因子”或“白细胞介素”。
