EXPRESSION OF PROLIFERATING CELL NUCLEAR ANTIGEN (PCNA) AND NUCLEOLARORGANIZER REGIONS (NORS) IN MULTIPLE-MYELOMA

We have studied 72 cases of multiple myeloma (MM) bone marrow trephine biopsies using the monoclonal antibody PC-10 and the colloid silver n itrate method for identification of proliferating cell nuclear antigen (PCNA) and nucleolar organizer regions (NORs), respectively. PC-10 an d AgNOR scores were statistically significantly different between low versus intermediate and low versus high grade of malignancy (P<0.001), whereas their difference was not significant between intermediate and high grade. A strong correlation was identified between these two pro liferation-associated indices in each histological grade. There is evi dence that the proliferative state of myelomas belonging to the interm ediate grade is approximately the same as that observed in high grade (blastic) ones.