Fish Immunology (1+1)

Unit 3- Nonspecific immunity

3.1. Nonspecific immunity
The innate immune system is believed to be the first line of host defense against invading pathogenic organisms and other foreign material. These components of the innate response are evolutionarily conserved in organisms lacking the typical adaptive immunity of vertebrates.
In fish, the innate immune response has been considered as an essential and primary component in combating pathogens due to limitations of the specific immune response and also their poikilothermic nature. The innate immune system is commonly divided into three compartments: the Physical (epithelial/mucosal) barrier, the humoral parameters and the cellular components.
The epithelial and mucosal barrier of the skin, gills and alimentary tract is an extremely important disease barrier in fish, being constantly immersed in media contain¬ing potentially harmful agents. This type of response requires a series of mecha¬nisms that involve humoral factors, cell and tissue, antimicrobial peptides and complement factors. Humoral factors may be cellular receptors or mol¬ecules that are soluble in plasma and other body fluids.