Recognizes an unidentified antigen in the cytoplasm of mat ure granulocytes. It shows no reactivity with any other cell type in human tissues. Markers of m yeloid cells are useful in the identification of different levels of cellular differentiation. Monoclonal antibody BM-2 reacts with early precursor and mature forms of human myeloid cells. This monoclonal antibody is useful for the detection o f myeloid leukemias and granulocytic sarcomas. It can be used as a marker of granulocytes in normal tissues or inflammatory processes.