Characterization of a monoclonal antibody specific to rainbow trout thrombocytes

A monoclonal antibody (MAb) specific for rainbow trout thrombocytes was pro duced and its reactivity was demonstrated by flow cytometry and immune-elec tron microscopy. Flow cytometry analysis showed that this MAb (TTL-7D11) re acted positively with about 30% of the peripheral blood leucocytes (PBL) an d about 1%, 2%, and 11% of the pronephros, mesonephros, and spleen cells, r espectively. Electron microscopy using immunogold labeling demonstrated tha t this MAb reacted strongly with thrombocytes, where gold beads could be se en attached only to the membrane and canalicular system of these cells. Pos itive and negative leucocytes for this MAb were obtained by magnetic cell s eparation. In the positive fraction, 96% of the cells were thrombocytes, wh ile in the negative fraction no more than 3% were, which clearly showed a h igh purity of the positive fraction. Aggregation studies showed that about 75% of the positive fraction cells aggregated after being mixed with U-4661 9 thromboxane-mimetic, whereas in the negative fraction only 10% of the cel ls did so. Thus, utilizing the TTL-7D11 we have succeeded in isolating a pu re thrombocyte population, and this would facilitate further studies, parti cularly an their characteristics and function(s). (C) 1999 Wiley-Liss, Inc.