Habicht G S, Beck G, Ghebrehiwet B
J Immunol. 1987 Apr 15;138(8):2593-7.
Although the existence and ubiquity of the C1q receptor is well established, its role in health and disease is largely unknown. Interleukin 1 (IL 1) is the major immunoregulatory molecule produced by macrophages and B lymphoblastoid cell lines. In this paper we present evidence that occupancy of C1q receptors by C1q on B lymphoblastoid cell lines inhibits "IL 1-like" activity, which is constitutively produced by these cells. When 5 X 10(6) Raji cells were cultured (24 hr at 37 degrees C) in the presence or absence of various concentrations of C1q (final concentration; 5 to 50 micrograms/ml) and the cellfree supernatants were analyzed for their effect on thymocyte proliferation by using the concanavalin A co-mitogenesis assay for IL 1, a statistically significant dose-dependent reduction of 3H-TdR incorporation was observed. Similar results were obtained when Daudi and Wil2WT cells were used, whereas Molt4, which is a T cell lymphoblastoid cell line, neither produced "IL 1-like" activity nor was affected by C1q. When immune complex-bound C1q was used instead of free C1q, inhibition of B cell IL 1 activity was also observed. Mixing experiments showed that Raji cells incubated with C1q released an inhibitor of IL 1-induced thymocyte proliferation. C1q alone had no effect on thymocyte proliferation in the presence or absence of human IL 1. In addition, the effect of C1q on IL 1 activity was abrogated either when the C1q was heat inactivated (56 degrees C, 60 min) or when the C1q was incubated with the cells in the presence of F(ab')2 anti-C1q. On the basis of these data, it is concluded that B cell receptor-bound C1q may play an important role in immunoregulation.
尽管C1q受体的存在及其普遍性已得到充分证实，但其在健康和疾病中的作用在很大程度上仍不清楚。白细胞介素1（IL-1）是巨噬细胞和B淋巴母细胞系产生的主要免疫调节分子。在本文中，我们提供证据表明，C1q在B淋巴母细胞系上占据C1q受体可抑制这些细胞组成性产生的“IL-1样”活性。当5×10⁶个拉吉细胞在存在或不存在各种浓度的C1q（终浓度；5至50μg/ml）的情况下培养（37℃，24小时），并使用伴刀豆球蛋白A共促有丝分裂试验检测白细胞介素1，分析无细胞上清液对胸腺细胞增殖的影响时，观察到³H-胸苷掺入量有统计学意义的剂量依赖性降低。当使用道迪细胞和威尔2WT细胞时，也得到了类似的结果，而莫尔特4细胞系是一种T细胞淋巴母细胞系，既不产生“IL-1样”活性，也不受C1q影响。当使用免疫复合物结合的C1q代替游离C1q时，也观察到对B细胞IL-1活性的抑制。混合实验表明，与C1q孵育的拉吉细胞释放出一种IL-1诱导的胸腺细胞增殖抑制剂。在存在或不存在人IL-1的情况下，单独的C1q对胸腺细胞增殖均无影响。此外，当C1q热灭活（56℃，60分钟）或当C1q在F(ab')₂抗C1q存在下与细胞孵育时，C1q对IL-1活性的影响被消除。基于这些数据，得出结论：B细胞受体结合的C1q可能在免疫调节中起重要作用。
