THE VALUE OF IMMUNOHISTOCHEMISTRY
IN THE ASSESSMENT OF BONE MARROW DISORDERS

Attilio Orazi, M.D., FRCPath. and Dennis P. O'Malley, M.D.

LYSOZYME The lysozyme antibody is polyclonal and is purified from rabbit antiserum. It is made by reacting the immunoglobin against urine of patients with monocytic leukemia. The antibody stains granulocytes and granulocyte precursors, as well as monocytes and macrophages. The stain works well in decalcified tissue both in formalin, Zenker and B5 fixed tissue. The lysozyme immunostain is a valuable stain, however, it suffers because it is not specific for granulocytes and because it does not stain all cells of the monocyte-macrophage series. In our experience, it stains only activated macrophages and not the more primitive cells of some of the monocytic and histiocytic series. In addition, it does not stain Langerhans cells. Among the stains for granulocytes, it is one of the most sensitive. But we have found that anti-myeloperoxidase is the preferable reagent with respect to the identification of granulocytes and granulocyte precursors. Clinical situations in which the stain may be used include: The recognition of granulocytes and cells of the monocyte macrophage series. References Krugliak L, Meyer PR, Taylor CR: The distribution of lysozyme, alpha-1-antirypsin, and alpha-1-antichymotrypsin in normal hematopoietic cells and in myeloid leukemias. Am J Hematol 1986;21:99. Pinkus GS, Said JW: Profile of intracytoplasmic lysozyme in normal tissues, myeloproliferative disorders, hairy cell leukemia, and other pathologic processes. An immunoperoxidase study of paraffin sections and smears. Am J Pathol 1997;89:351.