Humoral immune parameters in serum of gilthead seabream (Sparus aurata L.) after induced skin injury.

Skin lesions contribute to significant rates of morbidity and mortality in fish because they permit the entry of pathogens. Different seric immune parameters (IgM level, protease, antiprotease, peroxidase and lysozyme) and bactericidal activity (against Vibrio harveyi and Photobacterium damsealae) of gilthead seabream (Sparus aurata L.) specimens were evaluated after experimentally wounding fish in two body locations (above or below the lateral line). The results demonstrate that the level of several immune parameters present in fish serum (IgM, proteases, peroxidase and bactericidal activity) showed statistically significant variations depending on the site of the skin wound and the time post-wounding (from 0 to 7 days). However, other parameters (such as antiproteases or lysozyme) remained unaltered during the experiment and did not differs from the values recorded on control fish (non-wounded). The highest activities recorded coincided with the inflammatory healing phase. Moreover, many more significant variations were observed in fish wounded below the lateral line than in those wounded above the lateral line. The present results demonstrate the importance of skin integrity in the maintenance of fish body homeostasis.