Modulation of the chemiluminescence response of Mediterranean mussel (Mytilus galloprovincialis) haemocytes

The influence of several factors on the chemiluminescence (CL) activity of haemocytes from the Mediterranean mussel (Mytilus galloprovincialis) was st udied. Haemocytes were stimulated in vitro with different concentrations of zymosan, phorbol 12-myristate 13-acetate (PMA) and lipopolysaccharide (LPS ) (adding superoxide dismutase, SOD, to the zymosan-stimulated haemocytes i n order to test the specificity of the reaction). The in vitro effect of th e clam pathogens Vibrio tapetis (bacteria) and a Perkinsus atlanticus-like protozoan tentatively named Pseudoperkinsus taapetis on the mussel haemocyt es CL response was also assessed. To study the in vivo stimulation of haemo cytes, mussels were inoculated with zymosan and the CL response of their ha emocytes was subsequently measured. Zymosan added in vitro produced the hig hest CL response, although PMA also enhanced the CL emission and, in additi on, increased the zymosan-stimulated CL. LPS and S'. tapetis did not activa te haemocytes. SOD significantly decreased the CL emission in zymosan-stimu lated haemocytes. P. tapetis cells, as well as their extracellular products , inhibited the CL response to zymosan. Haemocytes from mussels injected wi th zymosan showed lower levels of stimulation than in vitro treated cells, and CL increased with time after injection. (C) 2000 Academic Press.