Tykocinski M L, Xiong N, Morrow D M
Department of Pathology, Case Western Reserve University, Cleveland, Ohio 44106-4943, USA.
Stem Cells. 1996;14 Suppl 1:240-5. doi: 10.1002/stem.5530140731.
A number of soluble and membrane-associated proteins are known to mediate platelet:leukocyte interactions. Platelet-derived factors that have attracted the most attention to date include transforming growth factor beta, interleukin 1 and platelet factor 4. Recently, we have uncovered another protein within platelets that has leukocyte modulatory activity. It was previously characterized as an endometrial glycoprotein named placental protein 14 (PP14) with suppressive effects upon lymphocyte proliferation, pro-inflammatory cytokine production and natural killer cell function. The "hematopoietic" PP14 derived from cells of the megakaryocytic lineage shares this immunosuppressive property, as evaluated by two-way mixed lymphocyte cultures. Interestingly, two alternatively spliced hematopoietic PP14 mRNAs have been cloned which differ in their encoded proteins. Cell-free translation and transfection analyses have verified the translatability of both PP14 mRNA species and allowed for the analysis of their glycosylation properties. PP14, a member of the lipocalin structural superfamily of proteins, now offers an intriguing new link between the coagulation and immune systems.
已知许多可溶性和膜相关蛋白可介导血小板与白细胞的相互作用。迄今为止，最受关注的血小板衍生因子包括转化生长因子β、白细胞介素1和血小板因子4。最近，我们在血小板中发现了另一种具有白细胞调节活性的蛋白。它以前被鉴定为一种子宫内膜糖蛋白，名为胎盘蛋白14（PP14），对淋巴细胞增殖、促炎细胞因子产生和自然杀伤细胞功能具有抑制作用。通过双向混合淋巴细胞培养评估，源自巨核细胞系细胞的“造血”PP14具有这种免疫抑制特性。有趣的是，已经克隆了两种选择性剪接的造血PP14 mRNA，它们的编码蛋白有所不同。无细胞翻译和转染分析证实了两种PP14 mRNA的可翻译性，并允许对其糖基化特性进行分析。PP14是脂质运载蛋白结构超家族的成员，现在在凝血系统和免疫系统之间提供了一个有趣的新联系。
