抗巨片形吸虫同型抗体在动物巨片形吸虫感染所致的抗体依赖性细胞介导的细胞毒反应( ADCC )免疫应答作用的研究

以印尼短尾羊（ITT）和美利奴细毛羊（Merino）两种品系的绵羊为实验动物，研究动物感染巨片形吸虫后所产生的抗体依赖性细胞介导的细胞毒反应的免疫应答。结果显示：对巨片形吸虫感染具有抗性的印尼短尾羊不产生特异性的IgG2，而易感品系的美利奴细毛羊感染巨片形吸虫后体内产生高滴度特异性IgG2抗体、特异性IgG2抗体在免疫应答中起着封闭抗体的作用，抑制巨噬细胞抗体依赖性细胞介导的细胞毒反应。由于印尼短尾羊不产生特异性IgG2抗体，对巨噬细胞抗体依赖性细胞介导的细胞毒反应不产生抑制作用，因此印尼短尾羊对巨片形吸虫的感染具有一定的抵抗力。使用纯化的IgG1和IgG2进行体外杀虫试验，结果IgG1有很强的促进体外杀虫效果，而自感染巨片形吸虫的美利奴细毛羊血清标本纯化的IgG2没有体外杀虫作用。体外实验还显示嗜酸性粒细胞在免疫血清、补体和IL-5的共同参与下具有较强的杀虫作用。

The Role of Antibody Isotypes Against Fasciola Gigantica In Immune Response With An Emphasis On Antibody Dependent Cell Mediated Cytoxicity

The study was carried out in two breeds of sheep, Indonesia Thin Tail (ITT) and Merino, both infected with F. gigantica. Kinetic analysis of Fasciola gigantica specific antibody responses revealed that resistant ITT do not produce a parasite specific IgG2 response; whereas susceptible Merino sheep produce a high parasite specific IgG2 response. The IgG2 produced in Merino sheep might act as a blocking antibody for antibody dependant cell mediated cytotoxicity by macrophages. Whereas, ITT appeared to down regulate IgG2 response, which might enable these sheep to possess an enhanced capacity of killing F. gigantica. The purified IgG1 and IgG2 were used in in vitro killing assays. IgG1 promotes the highest amount of killing compared to immune sera and IgG2 using purified Merino sera antibodies for in vitro killing assays. F. gigantica cultured in increasing amount of IgG1 had a trend of increasing the death rate. Parasites cultured in 10 ug/ml of IgG1 showed the highest amount of death. F. gigantica cultured in eosinophils with immune ITT sera (Day35) was 55% death after 24 hours. It should be that using purified eosinophils with immune ITT serum resulted in a strong trend of killing occurring in those wells which contained a combination of immune sera complement, IL-5 and eosinophils.