Potential use of bovine lactoferrin as adjuvant for the modulation of the specific immune response in rainbow trout (Oncorhynchus mykiss W.)

The present experiment was carried out in order to evaluate the potential adjuvant effect of bovine lactoferrin (bLF) in modulating the specific antibody (Ab) response to an exogenous protein, the human-gamma-globulins (H gamma G), injected intraperitoneally in rainbow trout Oncorhynchus mykiss (Walbaum 1792). Moreover, serum natural antibody (NatAb) level, serum total immunoglobulin (IgM) level and specific Ab response to bLF were also analysed. Experimental data showed that H gamma G is able to stimulate a specific Ab response when not adjuvanted with Freund's complete adjuvant (FCA), whereas bLF induces a specific Ab response only if adjuvanted with FCA. Statistical analyses revealed that neither bLF or FCA administered singly had significant effects on serum NatAb and IgM levels, whereas the specific immune response observed against H gamma G when adjuvanted with bLF was comparable to that achieved when FCA was used as the adjuvant. These results provide evidence of the potential for bLF to be used as an adjuvant for salmonids.