Incidence of apoptosis and cell proliferation in multiple myeloma: correlation with bcl-2 protein expression and serum levels of interleukin-6 (IL-6) and soluble IL-6 receptor.

Unlabelled: We evaluated the in vivo incidence of apoptosis and cell proliferation in multiple myeloma (MM) and investigated the correlation of both cellular events with histological tumour stage and grade, bcl-2 protein expression, serum IL-6 and sIL-6R.

Material And Methods: The TUNEL method was used to assess apoptosis and immunohistochemistry to assess the expression of proliferating cell nuclear antigen (PCNA) and bcl-2 protein in 30 bone marrow biopsy specimens. The apoptotic index (AI) and proliferative index (PI) were defined as the percentage of TUNEL and PCNA positive plasma cells, respectively.

Results: The mean AI was 0.162% and the mean PI 27.44%. A positive correlation between AI and PI was found (r = 0.44, P = 0.017). PI was also correlated with tumour grade (P = 0.015). The mean bcl-2 protein expression was 70% and did not correlate with AI or PI, but was higher in specimens taken at first diagnosis than in specimens taken after response to treatment (P = 0.035). The mean serum IL-6 and sIL-6R values were 9.43 pg mL-1 and 47.27 ng mL-1, respectively. These parameters did not correlate with AI or PI.

Conclusions: The results indicate that MM might be among the malignancies with very low incidence of apoptosis. Proliferative activity increased in parallel with tumour histological grade. A positive correlation between apoptosis and proliferation was observed, but the incidence of these two cellular events seems not to be related to the bcl-2 protein expression and the serum levels of IL-6 and sIL-6R.