Xavier R M, Nakamura M, Tsunematsu T
Third Division of Internal Medicine, Shimane Medical University, Izumo, Japan.
J Immunol. 1994 Mar 1;152(5):2624-32.
The monoclonal nonspecific suppressor factor (MNSF) is a lymphokine produced by a murine T cell hybridoma capable of suppressing Ab production by LPS-stimulated B cells. The existence of a human counterpart of MNSF, designated as the human nonspecific suppressor factor (hNSF), was likely because the anti-MNSF mAb (MO6) recognizes a similar suppressive activity in supernatants of Con A-stimulated human PBMC. By using the MO6 mAb, we investigated the presence of hNSF in the ascitic fluid of a patient with SLE. A small amount of cross-reactive hNSF was isolated from concentrated ascitic fluid fractionated with the MO6-affinity column, and a specific anti-hNSF mAb (P2) was produced. The hNSF eluted from the P2-affinity column could suppress up to 80% of the PWM-induced IgG production of human PBMC in a dose-dependent manner, even when added in late culture periods. Moreover, hNSF could inhibit proliferation of PBMC triggered by either PWM or Con A, which also implies an effect on T cells. On SDS-PAGE, the isolated hNSF resolved as a single peak of about 66 kDa and probably represents an aggregate of hydrophobic subunits. On reverse-phase HPLC, the bioactivity could be recovered from a single peak at 18.3 min. The suppression of IgG production induced by hNSF could be partly neutralized by preincubation with an anti-TCR-alpha mAb, whereas an anti-TCR-beta did not have any effect. Anti-TCR-alpha could also directly bind to the isolated nNSF, demonstrating some serologic relationship, as has been reported for several Ag-specific suppressor systems.
单克隆非特异性抑制因子（MNSF）是一种由鼠T细胞杂交瘤产生的淋巴因子，能够抑制脂多糖刺激的B细胞产生抗体。MNSF存在人类对应物，命名为人类非特异性抑制因子（hNSF），这很可能是因为抗MNSF单克隆抗体（MO6）在刀豆蛋白A刺激的人外周血单核细胞（PBMC）上清液中识别出类似的抑制活性。通过使用MO6单克隆抗体，我们研究了系统性红斑狼疮（SLE）患者腹水液中hNSF的存在情况。从用MO6亲和柱分级分离的浓缩腹水液中分离出少量交叉反应性hNSF，并制备了特异性抗hNSF单克隆抗体（P2）。从P2亲和柱洗脱的hNSF能够以剂量依赖的方式抑制高达80%的人PBMC由美洲商陆有丝分裂原（PWM）诱导的IgG产生，即使在培养后期添加也是如此。此外，hNSF能够抑制由PWM或刀豆蛋白A触发的PBMC增殖，这也暗示了对T细胞的作用。在十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）上，分离出的hNSF呈现为约66 kDa的单峰，可能代表疏水亚基的聚集体。在反相高效液相色谱（HPLC）上，生物活性可以从18.3分钟处的单峰中回收。hNSF诱导的IgG产生抑制作用可通过与抗TCR-α单克隆抗体预孵育而部分中和，而抗TCR-β单克隆抗体则没有任何作用。抗TCR-α也能直接与分离出的hNSF结合，表明存在一些血清学关系，正如在几个抗原特异性抑制系统中所报道的那样。
