The human granulocytes were isolated.Using hybridoma technique

a hybridoma cell line（HSN）producing monoclonal antibody against human granulocyte was obtained. The antibody belonged to IgG1 subclass.It was confirmed by immunohistochemical methods that HSN reacted selectively not only with human granulocytes

but also with their bone marrow precursors.Whereas human lymphocytes and red blood cells remained negative.No cross reaction was observed with peripheral blood cells in other animals.Its affinity constant was 5.7×108 L/mol

and the number of epitopes per granulocyte was 4.7×105.Monoclonal antibody displayed no loss of immunoreactivity after labelled with 99mTc.