Two subsets of peripheral blood plasma cells defined by differential expression of CD45 antigen

Abstract

Summary. The purpose of this study was to optimize the flow cytometric determination of circulating normal and malignant plasma cells (PC). We investigated peripheral blood (PB) samples of 65 patients with multiple myeloma or monoclonal gammopathy of unknown significance and 47 control subjects using CD38, CD45, B-B4, CD56, VLA-4, VLA-5 and CD19 monoclonal antibodies (MoAbs). Mono-or polyclonality was determined by staining of intracellular kappa and lambda light chains. Two subpopulations of PBPC were distinguished by differential expression of CD45. CD45 positive (CD45 þ ) PC showed a more immature morphology and were detected in all groups. They were polyclonal in the control subjects and either poly-or monoclonal in the myeloma patients. In contrast, CD45 negative (CD45 ¹ ) PBPC only occurred in myeloma patients and were consistently monoclonal, their presence being significantly associated with high disease activity (P < 0·001). Although detection of CD45 ¹ PBPC using CD38 or B-B4 MoAbs lead to similar results, CD45þ PBPC often were recognized to a lesser extent by B-B4 than by CD38 MoAbs.In conclusion, normal and malignant circulating PC can reliably be identified using CD38 and CD45 MoAbs. CD45 expression separates PBPC into two subsets of which the CD45 ¹ one only occurs in myeloma patients.

Competition between clonal plasma cells and normal cells for potentially overlapping bone marrow niches is associated with a progressively altered cellular distribution in MGUS vs myeloma

“…10 Alternatively, our results could also indicate that in order to spread the diseaseFlike normal BM PC 23,32,42 Fclonal PC could also leave the BM, recirculate into PB and home again into the BM at a different localization, in a kind of 'metastatic'/dissemination process. In line with this hypothesis, in this and other studies [7][8][9][10][11][12][13][14]43 circulating clonal PC were detected in a significant proportion of MGUS and SMM cases in addition to MM. A potential explanation for the recirculation of clonal PC in the early stages of the disease (for example, MGUS) could rely on the advanced age of MGUS patients, which could lead to lower numbers of available BM niches.…”

“…5,6 Despite the different tumor mass [7][8][9][10][11][12][13][14] and clinical behavior of the disease, clonal PC from MGUS, SMM and MM patients show highly similar and largely overlapping genetic profiles. [15][16][17] In addition, no clear phenotypic differences have been reported so far among clonal PC from MGUS, SMM and MM, 18 except for a few molecules involved in the interaction between PC and their microenvironment.…”

Analysis of circulating tumor cells in patients with multiple myeloma during the course of high-dose therapy with peripheral blood stem cell transplantation

“…11 The mature myeloma plasma cell has been described as a malignant population in PB. [22][23][24] In bone marrow, the myeloma plasma cells was characterized by the loss of CD19 expression. 25,26 Recently, the existence of CD19 Ϫ circulating plasma cells was demonstrated by FACS analysis.…”

Effects of the glucolipid synthase inhibitor, P4, on functional and phenotypic parameters of murine myeloma cells

“…The common leucocyte antigen, CD45, which has been shown to be most highly expressed on primitive and immature plasma cells and myeloma cells (Schneider et al, 1997), was not affected by P4 exposure. Taken together, the results suggest that tumour cells utilize GSLs extensively, but selectively, to maximize survival.…”

“…In complete contrast, Class II antigen expression was markedly increased by the inhibitor, with 4 µM P4 increasing expression almost tenfold (from 2 ± 0.4% to 14 ± 3%; P < 0.001). Approximately 90% of the cells were found to express the differentiation antigen, CD45, which is a marker for primitive to immature plasma cells/myeloma cells (Schneider et al, 1997), and this expression was not altered by P4 exposure regardless of the inhibitor concentration (Table 2). CD44 has been shown to be an important adhesion molecule for myeloma cell homing to the bone marrow and binding to bone marrow stromal cells, whereas CD54 (ICAM-1) appears to play only a minor role in this aspect of disease development (Okada and Hawley, 1995).…”