Alkaline phosphatase immunocytohistochemical staining using the MoAb LRP-56 of cytocentrifuged bone marrow cells containing >95% plasma cells of a patient with multiple myeloma. Cytospins were counterstained in diluted hemotoxiline. LRP immunoreactivity in a granular fashion in the cytoplasm is present in almost all plasma cells (A). Isotype control is negative (B).