[Significance of CD138/syndecan-1 for multiple myeloma immunophenotypes]

To establish the method of immunophenotyping testing for patients with multiple myeloma (MM), to analyze the characteristics of antigen expression on myeloma cells, and to purify primary myeloma cells, CD45/side scatter (SSC) gating tri-color immunofluorescence (IF) flow cytometry (FCM) was used to test immunophenotype of 18 patients with MM, 20 patients with acute leukemia (AL) and 7 normal controls. Purified primary myeloma cells were obtained by means of anti-CD138 monoclonal antibody and immunomagnetic microbeads. The results showed that myeloma cells displayed a CD45 negative/low positive expression, and SSC was located between nucleated red blood cells and neutrophils. Both CD138 and CD38 were positive while most antigens of T cell, B cell and myeloid cell were negative. Positive rate of CD56 was 83.3% and HLA-DR was 44.4% positive. Compared with MM patients, CD138 was negative and CD38 was 100% positive in AL patients. CD56 was 25% positive. In normal controls, neither CD138 nor CD56 was positive. The positive rate of primary myeloma cells after purification was 73%-95% with a mean of 86%. It is concluded that CD45/SSC gating procedure is a stable and reliable method to detect immunophenotype of MM. CD138 is a correspondingly special antigen for myeloma cells. Highly enriched primary myeloma cells can be obtained by anti-CD138 antibody and immunomagnetic microbeads.