Monoclonal antibody against complement component C3 of sea bass Dicentrarchus labrax: preliminary data

The complement system is composed of a series of plasma proteins that represents an important arm of immune innate system in both invertebrate and vertebrate animals. Complement can be activated by the classical antibody-dependent pathway, and by an "alternative pathway" that is triggered by a susceptible foreign surfaces such as bacteria (Lambris, 1990; Lambris et al., 1998). In the last years, a third pathway, the lectin pathway was discovered (Matsushita and Fujita, 1995). The cartilaginus fish, and all vertebrates, including teleost fish, amphibians, reptiles, birds and mammals have developed all three pathways of complement activation (Lambris et al., 1994). Among complement proteins, C3 component plays an important role in all activaction pathways. C3 has been purified from a large number of animal species, and it is of great interest to see that C3 in teleost fish show a hight degree of complexity that is not commonly present in mammalian species (Sunyer et al., 1998). In raimbow trout, for example, has been described the presence of multiple forms of functionally active C3 that differ in their binding efficiencies to various complement activating surfaces (Sunyer et al., 1996). Morever the alternative pathway complemen activity is 5 to lO fold higher in fish than in higher vertebrates (Sunyer and Tort, 1995). The increased number of C3 isoforms with ' the higher titer and activity, may expand the capacity of complement as a form ofinnate immunity to defend these animals against microorganisms in the aquatic environment. In the present study we have isoleted the third complement component from sea bass and used this fraction used this fraction to make an antibody against C3.