Human leukemia inhibitory factor (hLIF) is a cytokine of interleukin-6 family. This study aimed to evaluate the recombinant production rate of active hLIF by different vector-host systems under various conditions. Moreover, a rabbit polyclonal antibody (pAb) against recombinant hLIF (rhLIF) was produced and its anti-fertility effects were explored in Balb/c mice.

Four different constructs including pET22b/hLIF, pET28b/hLIF, pET32b/hLIF and pColdI/hLIF were designed and transformed into BL21-(DE3), Rosetta-(DE3), Origami-(DE3) and Shuffle T7-(DE3) host cells. The expression level and proliferative effect of rhLIF were measured by SDS-PAGE and MTT assays, respectively. Rabbit pAb to rhLIF was produced and characterized using enzyme-linked immunosorbent assay and western blot techniques. The Balb/c mice were divided into two intervention and control groups. Then, they were intraperitoneally injected by purified rabbit anti-rhLIF and non-immunized rabbit pAb, respectively. After sacrifice on day 7, the number of implantation sites was counted.

The rhLIF was successfully expressed by pET32b/hLIF and pColdI/hLIF vectors in all hosts with no significant difference in the rate of their expression. The rhLIF was purified and checked for activity. The results showed that it is functionally active and the produced anti-rhLIF pAb could specifically bind to commercial rhLIF. Passive immunization results showed that anti-rhLIF antibody completely inhibited fertility in all injected Balb/c mice compared to controls.

Although previous studies showed expression of rhLIF using various methods, using different vector-host systems ensures us of successful biological active expression of it. The pAb against rhLIF could be a powerful tool for inducing in vivo infertility.

人白血病抑制因子（hLIF）是白介素6家族的细胞因子。这项研究旨在评估在不同条件下，不同载体-宿主系统对活性hLIF的重组产生率。此外，产生了针对重组hLIF（rhLIF）的兔多克隆抗体（pAb），并在Balb / c小鼠中探索了其抗生育作用。

设计了四种不同的构建体，包括pET22b / hLIF，pET28b / hLIF，pET32b / hLIF和pColdI / hLIF，并将其转化为BL21-（DE3），Rosetta-（DE3），Origami-（DE3）和Shuffle T7-（DE3）宿主细胞。分别通过SDS-PAGE和MTT法测定rhLIF的表达水平和增殖作用。使用酶联免疫吸附测定和蛋白质印迹技术生产和鉴定了针对rhLIF的兔pAb。Balb / c小鼠分为两个干预组和对照组。然后，分别通过纯化的兔抗rhLIF和未免疫的兔pAb腹膜内注射。在第7天处死后，计数植入部位的数量。

在所有宿主中，pET32b / hLIF和pColdI / hLIF载体均成功表达了rhLIF，表达速率无明显差异。纯化rhLIF并检查活性。结果表明，它具有功能活性，并且产生的抗rhLIF pAb可以与商业rhLIF特异性结合。被动免疫结果显示，与对照组相比，抗rhLIF抗体完全抑制了所有注射的Balb / c小鼠的生育能力。

尽管以前的研究表明使用多种方法表达rhLIF，但使用不同的载体-宿主系统仍可确保我们成功地对其进行生物学活性表达。抗rhLIF的pAb可能是诱导体内不育的有力工具。