THE VALUE OF IMMUNOHISTOCHEMISTRY
IN THE ASSESSMENT OF BONE MARROW DISORDERS

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

APOPTOSIS BY IN-SITU END LABELING The rate of cell death due to apoptosis can be evaluated by a nonisotopic in situ end-labeling (ISEL) technique applied to paraffin sections. With this technique, residues of digoxigenin-nucleotides (digoxigenin-dUTP) are catalytically added to the fragmented (apoptotic) DNA by adding the enzyme TdT to the slides. The added residues are then immunostained by using an anti-digoxigenin peroxidase-conjugated antibody (Orazi et al, Mod Pathol, 1996). The peroxidase activity is then revealed by routine DAB staining. Apoptosis assessment may be of interest in evaluating bone marrow biopsies in patients with myelodysplastic syndromes and after cytokine treatment References Orazi et al: p53 overexpression in myeloid leukemic disorders is associated with increased apoptosis of hematopoietic marrow cells and ineffective hematopoiesis. Mod Pathol. 1996 9:48-52. Mangili et al: Staining apoptosis in paraffin sections. Advantages and limits. Anal Quant Cytol Histol. 1999; 21:273-6. Raza et al: Apoptosis in bone marrow biopsy samples involving stromal and hematopoietic cells in 50 patients with myelodysplastic syndromes. Blood. 1995; 86:268-76.