QUANTITATIVE IMAGE-ANALYSIS OF MIB-1 IMMUNOREACTIVITY - A COMPARISON WITH FLOW CYTOMETRIC ASSESSMENT OF PROLIFERATIVE ACTIVITY IN INVASIVE-CARCINOMA OF THE BREAST

Proliferative activity, especially flow cytometrically determined S-ph ase fraction, is generally accepted as an important prognostic indicat or in carcinoma of the breast. We studied cellular proliferation in 53 breast carcinomas using quantitative image analysis of immunoreactivi ty to a recently available monoclonal antibody, MIB-1, which is applic able to formalin-fixed, paraffin-embedded tissues. A MIB-1 is a murine monoclonal antibody that reacts with the Ki-67 nuclear antigen expres sed by proliferating cells in the late G1, and G2/M phases of the cell cycle. These results were compared to pow cytometric determinations o f S-phase and S + G2/M phase fractions obtained from corresponding fre sh tissue samples. There was a good correlation between quantitative i mmunoreactivity to MIB-1 as measured by image analysis and pow cytomet ric S-phase and S + G2/M phase fractions (r=.63, P<.00001; r=.607, P<. 00001, respectively). Immunoreactivity to MIB-1 and flow cytometric S- phase and S + G2/M phase fractions were significantly increased in ane uploid tumors as compared to diploid tumors. Histologic grade correlat ed with flow cytometric S-phase and S + G2/M phase fractions and MlB-1 immunoreactivity as determined by image analysis. There was a correla tion between tumor size and MIB immunoreactivity. No proliferative par ameters significantly correlated with lymph node status. Assessment of proliferative activity by quantitative image analysis of immunoreacti vity to monoclonal MIB-1 antibody may be employed in cases of invasive carcinoma of the breast in which flow cytometric analysis fails to re sult in quantitative proliferative values, or it may be used as an alt ernative measurement of such proliferative activity.