[Influence of immunomagnetic sorting on detecting genetic aberration of multiple myeloma cells by interphase fluorescence in situ hybridization].

This study was to aimed investigate the influence of immunomagnetic sorting on detecting the genetic aberrations of multiple myeloma (MM) by interphase fluorescence in situ hybridization (FISH) and to explore the detection method suitable to use in our country. The genetic aberrations of immunomagnetically sorted and unsorted bone marrow cells from the same MM patients were detected by interphase FISH and the detectable rate of genetic aberration was compared. The types of probes included 13 q14 (RB-1) and 14q32 (IGH). The 42 and 22 sorted and unsorted marrow samples from MM patients were detected by using 13q14 probe and 14q32 probes respectively, the results indicated that the 13q14 deletion was found in 9 of 42 (21.4%) unsorted marrow samples and in 25 of 42 (56.8%) CD138(+)-sorted marrow samples. The 13q32 rearrangement was found in 7 of 22 (31.8%) unsorted marrow samples and in 14 of 22(63.6%) CD138(+)-sorted marrow samples. Both of the difference was statistically significant (p = 0.001 and p = 0.035 respectively). Percentages of cytogenetic alterations detected in unsorted bone marrow cells correlated positively with percentage of plasma cells tested by bone marrow smears or flow cytometry. When percentage of plasma cells tested by bone marrow smears exceed 50%, or by flow cytometry exceed 10%, there was no difference between 2 methods. It is concluded that immunomagnetic sorting of CD138(+) cells increases the probability of detection of the 13q14 deletion and 14q32 rearrangement in bone marrow samples. The low detectable rate of genetic aberration in unsorted bone marrow cells is associated to the low percentage of plasma cells in bone marrow samples, higher percentage of plasma cells can partly overcome the shortage of unsorted detection method. When percentage of plasma cells tested by bone marrow smears exceed 50%, or by flow cytometry exceed 10%, there was no difference between 2 methods.