Cadmium (Cd) pollution is an important issue affecting the food safety of aquatic products. Cd can impair the immune system and cause irreversible damage to fish and other aquatic organisms. The immunoprotection activities of exogenous metallothionein (MT) and vitamin E (VE) were investigated in Cd poisoned grass carp, Ctenopharyngodon idellus, in the present study. C. idellus were divided into three groups: Cd+phosphate-buffered saline (PBS) group; Cd+MT; and Cd+VE. All fish were injected with cadmium chloride (CdCl₂) on the first day and then treated with PBS, MT or VE four days post-injection. Fish not injected with Cd were used as a negative control. Cd exposure caused severe head-kidney and splenic injury in C. idellus, mainly expressed as an increase in Cd content, histological damage, percentage of head-kidney and splenic cells apoptosis and decreases in immune-related gene mRNA transcript expression. However, MT and VE treatments protected against Cd-induced immunotoxicity in C. idellus by decreasing Cd contents, lessening histological damage, reducing the percentage of apoptosis and recovering immune-related mRNA transcript expression. Our results demonstrate that MT and VE can alleviate Cd-induced immunotoxicity and that MT has a more powerful effect than VE, indicating that MT could be a potential antidote in cases of Cd poisoning.

镉污染是影响水产品食品安全的重要问题。镉会损害免疫系统，对鱼类和其他水生生物造成不可逆转的损害。在本研究中，研究了镉中毒草鱼Ctenopharyngodon idellus中外源性金属硫蛋白（MT）和维生素E（VE）的免疫保护活性。C. idellus分为三组：Cd +磷酸盐缓冲盐水（PBS）组；Cd + MT；和Cd + VE。在第一天，所有鱼都注射了氯化镉（CdCl ₂），然后在注射后四天用PBS，MT或VE处理。未注射镉的鱼被用作阴性对照。镉暴露引起严重的头肾和脾损伤草鱼，主要表现为Cd含量增加，组织学损伤，头肾和脾细胞凋亡百分比以及免疫相关基因mRNA转录表达的降低。然而，MT和VE处理可通过降低Cd含量，减少组织学损伤，减少细胞凋亡百分比并恢复免疫相关的mRNA转录表达来保护Cd诱导的小肠念珠菌免疫毒性。我们的结果表明，MT和VE可以减轻Cd诱导的免疫毒性，并且MT具有比VE更为强大的作用，表明MT可能是Cd中毒的潜在解毒剂。