Leucocyte migration in rainbow trout (Oncorhynchus mykiss [Walbaum]): optimization of migration conditions and responses to host and pathogen (Diphyllobothrium dendriticum [Nitzsch]) derived chemoattractants.

A rainbow trout leucocyte-derived chemoattractant(s) was prepared and tested as a stimulant of leucocyte migration. It was used to optimize an in vitro leucocyte migration assay using a 48-well micro chemotaxis chamber. This assay has subsequently been used to test the chemoattractant activity of antigen extracts from the tegument of Diphyllobothrium dendriticum plerocercoids and conditioned medium obtained after in vitro maintenance of live plerocercoids. Leucocytes were found to have an increased directional motility (chemotactic response) to the host-derived chemoattractant(s) but a random increased motility (chemokinetic response) following stimulation/contact with parasite-derived antigens.