Separation of carp (Cyprinus carpio L.) thrombocytes by using a monoclonal antibody, and their aggregation by collagen

A monoclonal antibody against carp peripheral blood leucocytes was produced, and its reactivity analysed by flow cytometry and electron microscopy. The antibody reacted positively with 10–35% of the cells in a fraction of lymphocytes and thrombocytes that was separated by flow cytometry. Electron microscopy using immunogold labelling showed that this antibody reacted strongly with thrombocytes, but not with other leucocytes. By using a magnetic separator, leucocytes that were positive and negative for this antibody were separated. The positive cells were uniform, spindle-type cells that aggregated in the presence of collagen, while the negative cells did not aggregate. Light and electron microscopy showed that many positive cells changed to a spherical form after the addition of collagen and then 40–60% of these cells aggregated.