Assessment of Proliferative Activity of Plasma Cells in Multiple Myeloma

Overview

The assessment of proliferative activity of plasma cells in multiple myeloma has prognostic significance.The percentage of the proliferating plasma cells (plasma cell labelling index - PCLI) at thetime of the diagnosis correlates with survival, and is increased during transition from the plateauphase to the relapse. Flow cytometry and immunofluorescence examination of bone marrowaspirates are used for the assessment of the PCLI. This study describes a method for evaluation ofPCLI in formalin-fixed, paraffin embedded material. Bone marrow biopsies from 31 patients withrelapsing (n=10) and newly diagnosed (n=21) multiple myeloma were examined by double immunohistochemicalstaining: anti-CD 138 (Syndecan 1) and anti - Ki-67. The percentage of plasmacells positive for Ki-67 were counted by an image analysis system. New cases of multiple myelomashowed 0.7 to 12.7% positivity of Ki-67 labelled plasma cells (median 4.75), the relapsing casesshowed 4.4 to 22.4% positivity (median 7.75). Statistic analysis revealed prognostic significance(p=0.046).This study presents a new method for assessment of proliferative activity of plasma cells, whichcan be used on archived formalin-fixed, paraffin embedded material.

Key words:
multiple myeloma - proliferation - Ki-67 - immunohistochemistry - Plasma Cell LabellingIndex (PCLI)