Contributions
Abstract: EP1048
Type: E-Poster Presentation
Session title: Myeloma and other monoclonal gammopathies - Clinical
Background
The improvement and practical application of high-sensitive molecular biological assays to detect of tumor cells has made it possible not only to determine the circulating tumor cells (CTCs) in the peripheral blood and to measure them quantitatively, but also to analyze their morphological and immunophenotypic characteristics. The use of multi-color flow cytometry makes it possible to characterize the biological features of tumor myeloma cells not only in the bone marrow, but also to identify the population of such cells in the peripheral blood.
Aims
The aim of the study was to investigate the immunophenotypic features of bone marrow tumor plasma cells (BM PLCs) and circulating tumor plasma cells in multiple myeloma (CTC MM) in comparison with the clinical features of the disease.
Methods
: A parallel immunophenotypic study of bone marrow (BM) and peripheral blood (PB) samples was performed in 34 patients with a newly diagnosed MM by 4-color flow cytometry (FACSCalibur (Becton Dickinson, USA). Bone and extramedullary plasmocytomas were detected in 10 MM patients with stage III disease, and chronic renal failure (CRF) was detected in 24 patients. The isolation of tumor PLCs was carried out from a gate of CD38-positive (bright) plasma cells against a lateral light scattering (SSC) signal, and at least 500,000 events were included in the analysis. The expression of CD138, CD45, CD56, CD19, CD20, CD79b, CD11c, CD33, CD28, CD117 was determined. Quantitative assessment of PLCs was carried out by the content of CD38+(bright) cells in terms of all nucleated cells of BM and/or PB.
Results
In all patients with newly diagnosed MM, CTCs MM was characterized by significantly lower expression of CD138, CD56, CD28, and CD79b compared to BM PLCs.
The immunophenotypic profile of CTCs compared to BM PLCs in patients with plasmocytomas was characterized by a significant decrease (p=0.0003) in the expression of syndecan-1 (CD138), and a significant (p=0.0004) increase in the content of CD138-negative and CD19-positive PLCs in the population. In patients with MM, not complicated by plasmocytomas, a significant (p=0.03) decrease in the expression of CD138 and CD28 (p=0.02) in the CTCs compartment was revealed. CD79b expression on CTCs MM was significantly more frequently detected in extramedullary plasmocytomas. When comparing BM PLCs in MM patients with or without kidney lesions, no significant differences in the frequency of antigens were obtained. The high content of PLCs positive for CD138, CD56, CD11c, CD28, CD79b was noted. CTCs MM in patients with renal lesions were characterized by the same phenotype as BM PLCs, as well as significantly more frequent positive expression of CD56. CTCs MM in patients with MM without impaired renal function were characterized by reduced expression of CD138, CD28. Thus, in the case of kidney damage in patients with MM, a large number of cells positive for CD138, CD56, CD28 enter the circulation, which is not observed in the absence of this complication.
Conclusion
Our study has shown that in MM with a complicated course, the identified CTCs subclone has a unique immunophenotypic protein expression profile, characterized by a less 'mature' phenotype and variable expression of adhesive molecules (CD138, CD56), which increases their ability to enter the peripheral blood from the bone marrow and cause extramedullary lesions. The data obtained are consistent with the literature data on the significant role of CD138-negative cells in MM, less 'mature' phenotype, and resistance to chemotherapy.
Keyword(s): CD38, CD56, Cytometry, Multiple myeloma
Abstract: EP1048
Type: E-Poster Presentation
Session title: Myeloma and other monoclonal gammopathies - Clinical
Background
The improvement and practical application of high-sensitive molecular biological assays to detect of tumor cells has made it possible not only to determine the circulating tumor cells (CTCs) in the peripheral blood and to measure them quantitatively, but also to analyze their morphological and immunophenotypic characteristics. The use of multi-color flow cytometry makes it possible to characterize the biological features of tumor myeloma cells not only in the bone marrow, but also to identify the population of such cells in the peripheral blood.
Aims
The aim of the study was to investigate the immunophenotypic features of bone marrow tumor plasma cells (BM PLCs) and circulating tumor plasma cells in multiple myeloma (CTC MM) in comparison with the clinical features of the disease.
Methods
: A parallel immunophenotypic study of bone marrow (BM) and peripheral blood (PB) samples was performed in 34 patients with a newly diagnosed MM by 4-color flow cytometry (FACSCalibur (Becton Dickinson, USA). Bone and extramedullary plasmocytomas were detected in 10 MM patients with stage III disease, and chronic renal failure (CRF) was detected in 24 patients. The isolation of tumor PLCs was carried out from a gate of CD38-positive (bright) plasma cells against a lateral light scattering (SSC) signal, and at least 500,000 events were included in the analysis. The expression of CD138, CD45, CD56, CD19, CD20, CD79b, CD11c, CD33, CD28, CD117 was determined. Quantitative assessment of PLCs was carried out by the content of CD38+(bright) cells in terms of all nucleated cells of BM and/or PB.
Results
In all patients with newly diagnosed MM, CTCs MM was characterized by significantly lower expression of CD138, CD56, CD28, and CD79b compared to BM PLCs.
The immunophenotypic profile of CTCs compared to BM PLCs in patients with plasmocytomas was characterized by a significant decrease (p=0.0003) in the expression of syndecan-1 (CD138), and a significant (p=0.0004) increase in the content of CD138-negative and CD19-positive PLCs in the population. In patients with MM, not complicated by plasmocytomas, a significant (p=0.03) decrease in the expression of CD138 and CD28 (p=0.02) in the CTCs compartment was revealed. CD79b expression on CTCs MM was significantly more frequently detected in extramedullary plasmocytomas. When comparing BM PLCs in MM patients with or without kidney lesions, no significant differences in the frequency of antigens were obtained. The high content of PLCs positive for CD138, CD56, CD11c, CD28, CD79b was noted. CTCs MM in patients with renal lesions were characterized by the same phenotype as BM PLCs, as well as significantly more frequent positive expression of CD56. CTCs MM in patients with MM without impaired renal function were characterized by reduced expression of CD138, CD28. Thus, in the case of kidney damage in patients with MM, a large number of cells positive for CD138, CD56, CD28 enter the circulation, which is not observed in the absence of this complication.
Conclusion
Our study has shown that in MM with a complicated course, the identified CTCs subclone has a unique immunophenotypic protein expression profile, characterized by a less 'mature' phenotype and variable expression of adhesive molecules (CD138, CD56), which increases their ability to enter the peripheral blood from the bone marrow and cause extramedullary lesions. The data obtained are consistent with the literature data on the significant role of CD138-negative cells in MM, less 'mature' phenotype, and resistance to chemotherapy.
Keyword(s): CD38, CD56, Cytometry, Multiple myeloma