未甲基化CpG oligodeoxyribonucleotides (ODNs) 可活化哺乳類動物免疫系統，也已經在哺乳類動物做過非常多的試驗。而目前也已經有研究指出CpG ODNs亦可以活化魚類免疫系統。在魚類中CpG ODNs可以誘導抗病毒細胞激素產生，提高非特異性毒殺細胞產生、活化一些免疫相關基因，如：IFN, IL-1, IL-12，及間接誘導細胞遷移與提高血清中溶菌酶產生。本實驗選用在南台灣養殖業常見的魚種金目鱸魚(Lates calcarifer) 做為材料來研究使用CpG ODNs來誘導產生細胞激素。 CpG ODNs可以誘導鳟魚頭腎細胞增生及促使頭腎細胞產生細胞增生因子(PIFs)，進而促使細胞增生。當B細胞移除後，以CpG ODNs刺激鳟魚頭腎細胞仍會促使細胞增生。這結果顯示，PIFs非由B細胞產生其作用標的亦非B細胞。因此在本研究中將試圖尋找PIFs之來源及作用標的細胞？此外，也希望可以純化及鑑別出PIFs為何？本研究結果顯示經由CpG ODNs刺激後，吞噬性細胞會產生蛋白質PIFs，誘導淋巴細胞中某一族群的增生。當吞噬性細胞移除後，PIFs並不能促使細胞增生，因此吞噬性細胞在此反應中也同時扮演如同是輔助性細胞角色。 The effects of unmethylated CpG oligodexynucleotides (ODNs) on the mammalian immune system are relatively well studied. CpG ODNs have been shown to induce a variety of different immune responses in fish including IFN / induction along with antiviral activity, macrophage activation, cytokine production and activation of other immune-related genes and cell proliferation.
CpG ODNs can indirectly inducing cellular migration in vitro and enhancing serum lysozyme activity in vivo. Sea bass (Lates calcarifer), a common economical aquaculture species in south Taiwan, was chosen as the objective in this study to investigate cytokines induced by CpG ODNs. Previous studies showed that CpG ODNs can induce trout head kidney cells to produce proliferation inducing factors (PIFs), and then result in cell proliferation. However, B cells depletion did not affect the responses of trout head kidney cells to CpG ODNs stimulation. These results indicate that neither the source of the proliferation-inducing factors or the proliferating responder cells are B cells. The aims of our study are to find the source of PIFs and their target cells. Furthermore, we would try to purify and identify of the proliferation-inducing factors. Our results showed PIFs were proteins secreted by CpG ODNs stimulated phagocytes, and PIFs induced a subpopulation of lymphocyte to proliferate. Besides, phagocytes were supposed to act as accessory cells in this response.