ABSTRACT
The immune system of vertebrates is composed of numerous distinct and interconnected elements. Each and every part has its own basic defensive value, and the eventual union of these parts is likely to be related to animals’ immunologic record and evolution. The basic immune components, like Ag-recognizing lymphocytes, immunoglobulins, products of major histocompatibility complex and recombination activation genes, and the recombination processes, are alike in fish and mammals. These immune molecules and immunity mechanisms explained the immune system repository and adaptive radiations. Vertebrate immune system consists of both systemic and mucosal immune compartments. The mucosal immune system protects the body from the first encounter of pathogens. In this chapter, we will discuss about antigens and immune responses in fishes. Interest in antigens and immune response in fishes arise from a need to develop health care tools to help a growing fish aquaculture industry while at the same time conveying queries regarding the origins and evolution of immunity in vertebrates. Increased knowledge of the fish immune system will ease the success of many researches and discoveries.
