Production of a monoclonal antibody for carp (Cyprinus carpioL.) phagocytic cells and separation of the cells

A monoclonal antibody (MAb; TCL-BE8) for carp peripheral blood leucocytes (PBL) was produced, and its reactivity was analysed by electron microscopy and flow cytometry. Electron microscopy using immunogold labelling showed that this MAb reacted with neutrophils and monocytes. The antibody reacted with 98% of the cells in a fraction of granulocytes separated by flow cytometry. The antigen detected by this was MAb defined as a membrane protein of Mr of 112 kDa. Using a magnetic separator, cells reactive with this antibody were separated from leucocytes with a density of 1·08 g ml−1or 1·08–1·09 g ml−1. MAb-positive cells in the PBL with a density of 1·08 g ml−1consisted of a mixture of neutrophils and monocytes, whilst in PBL with a density of 1·09 g ml−1they consisted of only neutrophils. The MAb-negative fractions contained mainly lymphocytes and thrombocytes. The MAb-positive cells showed strong phagocytosis, which is a characteristic function of neutrophils and monocytes, but this was absent from the MAb-negative fraction. Purification of monocytes and neutrophils, or isolation of neutro-phils, can be achieved by using this MAb allowing more effective analysis of the carp leucocyte functions.