[Immunohistochemical evaluation of the percentage of proliferating neoplastic cells of Wilms' tumor in children by means of the MIB-1 monoclonal antibody].

Quantifying the proliferation of neoplastic cells is an important and objective element in estimating the degree indicating the malignancy of neoplasms and their reaction to applied treatment. The basic problem in the procedure dealing with the Wilms' tumors in children is the classification of patients into appropriate risk groups. The goal of this study was to explore the possibility of determining the proliferation index in Wilms' tumors with the aid of monoclonal antibody MIB-1. The material comprised segments of the tumors taken from 35 children treated at the Children and Youth Oncology Clinic of the Mother and Child Institute in Warsaw as well as at the Pediatric Surgery Clinic of the Pomeranian Medical Academy in Szczecin in the years from 1982 to 1994. Specimens for immunohistochemical investigations were prepared from the tissues of tumors, fixed in paraffin and embedded in paraffin blocs. The positive response of the reaction for the Ki-67 antigen was visible in the form of red-stained granules (Figs. 1, 2, 3, 4). The index for proliferation of the cell nuclei was determined in the individual components of the tumors: blastema, epithelial tissue and stroma. Distinct difference was disclosed to exist between low values for stromal cells (3.3%) and high ones for blastemic cells (22.3%) and epithelial cells (23.7%). The post chemotherapy group revealed higher values of the index within the epithelial cells and lower among blastemic cells as compared to the group without chemotherapy. The prognostic significance of the proliferation index when using monoclonal antibody MIB-1 was studied by dividing the tumors into two groups, namely: below and above 20% of the index value. It was noticed that there was a concurrency of higher proliferation values among blastemic and epithelial cells with worse prognosticating cases. The cases, in which after chemotherapy the index of proliferation within blastema persisted being high, were recorded to predict poorer prognosis.