特异性IgG抗体作为宿主抗约氏疟原虫再感染关键效应分子的研究

目的探讨再感染早期宿主保护性免疫应答的相关机制。方法采用致死型约氏疟原虫(Plasmodiumyoelii 17XL,Py17XL)感染抵抗型DBA/2小鼠,待全部小鼠自愈后用同种疟原虫株再次攻击。吉姆萨薄血膜染色法观察小鼠原虫血症水平;被动转移实验评估免疫血清的保护性作用;流式细胞仪检测脾中T、B细胞亚群动态变化。结果2/3小鼠能够完全抵御同种疟原虫再感染,仅1/3小鼠出现一过性低水平原虫血症,且于再感染后第8d自愈;免疫血清显著抑制初次感染小鼠原虫血症水平并延长其生存期;与初次感染相比,再感染早期脾CD4+T细胞、B220+和B220lowCD138+(浆细胞)亚群数目显著增加。结论特异性IgG抗体在宿主抗再感染免疫中发挥重要作用,记忆性T、B细胞可能为宿主保护性免疫应答的关键参与者。

Specific IgG antibodies play a key role in resisting re-infected with Plasmodium yoelii

To investigate host protective immune mechanisms during the early stages of re-infection with malaria parasites,resistant DBA/2 mice were infected with Plasmodium yoelii 17XL(Py17XL),and infections were allowed to progress naturally.Following self-clearance of parasites,mice were subsequently re-infected with the same strain.The level of parasitemia in mice during re-infections was followed by Giemsa stained thin-smear microscopy.Passive transfer experiments were carried out to evaluate the protective properties of immune sera.Flow cytometry was used to detect dynamic changes in T and B cell subsets in the spleen of re-infected mice.2/3 mice were completely protected against re-infection,and 1/3 exhibited low levels of transient parasitemia which was cleared by day 8.Passive transfer of immune sera significantly inhibited the parasitemia of naive mice,and prolonged their survival period;compared with primary infections,the number of CD4 T,B220 and B220 lowCD138 (plasma cells)increased significantly during the early stages of re-infection.Specific IgG antibodies play a key role in resisting re-infection,and memory T,and B cell subsets may be major factors of host protective immunity.