The influence of natural immunostimulant on some indicators of specific immunity of carp

An important aspect of industrial fish farming is the increase in technogenic influence on the habitat of aquatic organisms, which suppresses the functions of the fish immune system or promotes the development of hypersensitivity and autoimmune reactions due to disruption of the mechanisms of immune system regulation, which leads to disruption of the homeostasis of the fish organism. Due to the tense environmental situation, including aquatic ecosystems, the search for environmentally safe immunostimulants necessary to maintain the organism's homeostasis and its correction is urgent. The search was conducted on carp (Cyprinus carpio) in aquarium conditions. The main hydrochemical parameters corresponded the fishery standards. The investigation was conducted for 5 – 10 – 15 – 20 days using the preparation in different doses: 5 – 10 – 15 mg per kilogram of fish weight. Thus, 4 groups were formed: a control and three experimental groups. The results of investigation of the influence of an immunostimulant of natural origin on immunological indicators are presented. The relationship between humoral and cellular immunity when using the immunostimulant in different doses and time ranges is searched. It was set up that the optimal dose of the preparation is 10 mg/kg of fish weight, which leads to an increase in the level of immunoglobulins, T- and B-lymphocytes without changes in the content of circulating immune complexes. Their ratio varies depending on the dose and duration of preparation use. Analyzing the data got over time, a significant increase in the number of immunocompetent cells investigated was observed on the 15th-20th day of preparation use. Researches have not revealed a negative influence of the preparation on regulatory T-cells, which indicates a normal course of immune response regulation. The activation of the biosynthesis of immunoglobulins indicates an increase in the tension of humoral immunity. However, such an increase in the humoral component of the immune response is not the result of an increasing antigenic load, since the searches were conducted in aquarium conditions. Evidence of this fact is the absence of significant changes in the level of circulating immune complexes at different doses of the immunostimulant and the period of its use, given that circulating immune complexes characterize the degree of interaction of the antigen-antibody complex in the animal organism and are directed at eliminating pathogens. The use of the immunostimulating preparation had a beneficial influence on the level of cellular and humoral immunity of fish. This was reflected in an increase in the level of total T-lymphocytes, active T-lymphocytes, B-lymphocytes and immunoglobulins. An effective immunostimulating effect was achieved at a dose of 10 mg/kg of fish weight with a duration of use of the preparation  for 15–20 days. Research into optimal preparation doses for different age groups and sizes of fish will help determine the most effective doses for different categories of carp. In addition, it is important to conduct searches on other fish species to evaluate the efficacy of the investigational preparation and its potential use in different aquaculture systems. It is also actual to further investigation the possibility of combined use of the preparation with other immunostimulants or therapeutic preparation to enhance the overall immune defense of fish. An important aspect is the research of the ecological influence of the use of the immunostimulant in fish farming, including the possibility of its accumulation in aquatic ecosystems and the influence on other aquatic organisms.