THE VALUE OF IMMUNOHISTOCHEMISTRY
IN THE ASSESSMENT OF BONE MARROW DISORDERS

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

OTHER T-CELL MARKERS: CD2, CD7, TIA-1 Although these antibodies can be used to stain paraffin embedded tissues, only limited information is available concerning their applicability to bone marrow biopsies. CD2 and CD3 reactivities overlap in most cases. CD7 requires a special pre-treatment: biotinylated-tyramide enhancement (Merz et al, 1995). The pattern of expression of TIA-1, a monoclonal antibody that recognizes granular structure in cytotoxic T lymphocytes, may help in distinguishing large granular lymphocyte leukemia (high expression of TIA-1) from reactive T cell lymphocytosis and other T cell diseases (low expression of TIA-1). However, the diffuse expression of TIA-1 seen in the usually numerous granulocytes present in the marrow cavities may completely mask the presence of a small population of TIA-1 positive cytotoxic T cells. References Malisius et al: Constant detection of CD2, CD3, CD4, and CD5 in fixed and paraffin-embedded tissue using the peroxidase-mediated deposition of biotin-tyramide. J Histochem Cytochem. 1997;45:1665-72. Merz et al: ImmunoMax. A maximized immunohistochemical method for the retrieval and enhancement of hidden antigens. Lab Invest. 1995 Jul;73:149-56.