Expression of Ki-67/MIB-1 in Bone Marrow Biopsies from Patients with Myelodysplastic Syndromes and Aplastic Anemia

Lee, Jeong Nyeo; Park, Jong In; Kim, Myeong You

Abstract

BACKGROUND: Sometimes myelodysplastic syndrome (MDS) is especially difficult to distinguish from acquired aplastic anemia (AA) because of the clinical, cytologic, and histologic similarities of these two disorders. The proliferative activity of the hematopoietic cells is very different in various hematologic disorders and Ki-67 expression in the bone marrow cells is an useful cell proliferation marker. We tried to evaluate the significance of Ki-67/MIB-1 immunoreactivity in the discrimination of MDS and AA.
METHODS
Bone marrow biopsy specimens from 56 individuals, 7 controls, 21 with MDS, 16 with AA and 12 with acute leukemia were obtained in Pusan Paik Hospital. Immunohistochemial staining for Ki-67 antigen was assessed by the MIB-1 monoclonal antibody using a microwave oven-based antigen retrieval technique.
RESULTS
The mean values (+/-SD) of Ki-67 positive cells was as follows: control group, 16.8+/-3.6%; MDS, 25.3+/-10.1%; AA, 5.1+/-2.9%; acute leukemia, 30.5+/-10.4%. MDS cases showed statistically higher values of Ki-67 than did those of AA cases and control group (P<0.001) but no significance in Ki-67 frequencies was observed between the cases of MDS and acute leukemia.
CONCLUSIONS
In the bone marrows of MDS cases the Ki-67 positive cells were frequently observed, suggesting high proliferative activity even in the nonleukemic state, while most of the bone marrows in AA showed very low proliferative activity. Thus immunohistochemical staining with Ki-67/MIB-1 would be useful in the discrimination of AA and MDS by the difference of Ki-67 positive cell percentage in the bone marrow.