A new method for the analysis of plasma cell DNA content in multiple myeloma samples using a CD38/propidium iodide double staining technique.

In the present paper a CD38/propidium iodide double staining technique is described which separately assesses the cell cycle distribution of myelomatous plasma cells from that of the residual normal hemopoietic cells. For this purpose, bone marrow (BM) cells from a group of 42 untreated multiple myeloma patients were analyzed. Of these, 23 cases were aneuploid (55%) and 19 diploid (45%). The use of the CD38/propidium iodide double staining method allowed a clear separation between CD38 strong positive cells from the remaining bone marrow populations, cell sorting experiments confirming that plasma cells were almost exclusively contained in the former fraction where they represented 97 +/- 2% of the total cells sorted. In all cases, the S-phase in plasma cells and in the remaining normal hemopoietic bone marrow cells was assessed, being higher in normal hemopoietic cells (8.0 +/- 6.3%) than in plasma cells (3.3 +/- 2.6%, P < 0.002). In addition, there was no correlation between the S-phase of the neoplastic and normal bone marrow cells (r = 0.22; P > 0.10); this work therefore shows that the assessment of the total proliferative rate of bone marrow samples does not reflect either the proliferation of normal cells or that of neoplastic plasma cells but will depend on the proliferative rate and the percentage of each population within the sample, which can be assessed by the technique described here.