ROLE OF GROWTH FACTORS IN EBV-POSITIVE POST-TRANSPLANT L

淋巴增生性疾病涉及自然感染EB病毒(EBV)的B细胞，是消融治疗的破坏性并发症。本项目旨在阐明生长因子在EBV阳性淋巴增生性疾病发展中的作用。EB病毒(EBV)对B细胞的永生化和感染B细胞在体外的持续生长依赖于B细胞分泌培养上清液中的生长因子以及感染病毒的B细胞对这些因子的利用。实验室的一个主要兴趣是鉴定在EBV永生化细胞中负责自分泌生长因子活性的化合物及其在B细胞永生化/转化中的作用。最初，我们确定白介素6(IL-6)是EBV永生化B细胞产生的一种自分泌生长因子。随后，我们确定乳酸是另一种更丰富、更有效的自分泌生长因子，由EBV永生化的B细胞产生。最近，我们将重点放在PEL的生长因子需求上，这是一种经常合并EBV和KSHV感染的原发渗出性淋巴瘤。这些淋巴瘤发生在免疫抑制的艾滋病患者中，预后非常差。利用来自PEL的永生化细胞系，我们已经确定人IL-10和病毒IL-6，而不是人IL-6，是这些细胞系的自分泌生长因子。因此，抗人IL-10和病毒IL-6的中和抗体可以深刻地抑制PEL细胞的自发增殖。我们在NIH3T3中表达了病毒IL-6，并将其接种到裸鼠体内。利用这个实验系统，我们还鉴定了病毒IL-6的其他生物学特性。这种细胞因子促进髓系、红系和巨核系的造血；促进脾和淋巴结的浆细胞增多；促进肝脾肿大；促进多克隆性高丙种球蛋白血症；增加血管内皮生长因子的产生。抗小鼠血管内皮生长因子的中和抗体可预防免疫抑制的小鼠接种PEL后发生PEL。提示病毒IL-6和血管内皮生长因子在PEL的发病机制中起重要作用。

Lymphoproliferative diseases involving B cells naturally infected with Epstein-Barr virus (EBV) are devastating complications of ablative therapies. This project aims to clarify the contribution of growth factors to the development of EBV-positive lymphoproliferative diseases. B cell immortalization by Epstein-Barr virus (EBV) and the continuous growth of B cells infected with EBV in vitro is dependent upon B cell secretion of growth factors in the culture supernatant and utilization of these factors by B cells infected with the virus. A major interest of the laboratory has been the identification of the compounds responsible for autocrine growth factor activity in EBV-immortalized cells and their role in B-cell immortalization/ transformation. Initially, we identified Interleukin-6 (IL-6) as one of the autocrine growth factors produced by EBV-immortalized B cells. Subsequently, we identified lactic acid as being another, more abundant and more potent autocrine growth factor produced by EBV-immortalized B cells. More recently, we have focused on growth factor requirements of PEL, primary effusion lymphomas which are often coinfected with EBV and KSHV. These lymphomas arise in immunosuppressed individuals with AIDS and have a very poor prognosis. Using immortalized cell lines derived from PEL, we have identified human IL-10 and viral IL-6, but not human IL-6, as autocrine growth factors for these cell lines. Thus, neutralizing antibodies against human IL-10 and viral IL-6 profoundly inhibit the spontaneous proliferation of PEL cells. We have expressed viral IL-6 in NIH3T3 and inoculated these cells into athymic mice. Using this experimental system, we have identified other biological properties of viral IL-6. This cytokine promotes hematopoiesis in the myeloid, erythroid, and megakaryocytic lineages; plasmacytosis in spleen and lymph nodes; hepatosplenomegaly; polyclonal hypergammaglobulinemia; and increased production of VEGF. Neutralizing antibodies against murine VEGF prevented PEL development in immunosuppressed mice inoculated intraperitoneally with PEL. This suggests that viral IL-6 and VEGF play an important role in PEL pathogenesis.