Non-specific immune response of healthy and immunocompromised Asian catfish (Clarias batrachus) to several immunostimulants

The present study was performed to determine the efficacy and immunoreversal effects of four well-known dietary immunomodulators viz., lactoferrin, β-1,3 glucan, levamisole and vitamin C on the innate immune response of healthy and cyclophosphamide (CYP) induced immunocompromised Asian catfish, Clarias batrachus. Fish specimens were divided into 5 groups and each group was fed with diets supplemented with or without an appropriate dose of immunostimulant. Cyclophosphamide at a rate of 200 mg/kg body weight was injected intraperitoneally for 3 consecutive days to induce an immunocompromised state in control fish. After 72 h post injection, fish of all the groups were bled and innate immune parameters, both humoral (haemagglutination titre and total serum myeloperoxidase content) and cellular (respiratory burst and phagocytic activities), were determined. The results showed that all the substances delivered as feed supplements significantly (P < 0.05) enhanced most of the non-specific immune parameters in both healthy and immunosuppressed subgroups compared to their respective controls. Levamisole induced significantly increase in blood phagocytic activities in both healthy and immunocompromised fish as observed from raised respiratory burst and myeloperoxidase activity as compared to control. Feeding of vitamin C significantly enhanced phagocytic activity and myeloperoxidase content. On the other hand, all parameters were positively influenced by lactoferrin and glucan feeding in both groups compared to their respective controls.