Figure 1. EasySep™ Human Bone Marrow CD138 Positive Selection Kit Enriches CD138+ Cells in Bone Marrow Specimens from Multiple Myeloma Patients

A clinical study was conducted using the EasySep™ Human Bone Marrow CD138 Positive Selection Kit on 33 clinical bone marrow specimens from multiple myeloma patients at various stages of the disease. The mean CD138+ cell purity, as measured by flow cytometry by gating on CD38+/CD138+ cells, was 12.9% (range 0.2% - 82.7%) in unenriched specimens and increased to 79.6% (range 18.5% - 98.6%) in the EasySep™-enriched specimens. In the representative patient bone marrow specimen above, the purities of the unenriched and final enriched plasma cell fractions were 6.0% and 82.4%, respectively.

Figure 2. Percentage of Abnormal Nuclei Counted in Plasma Cells Before (Unenriched) and After Enrichment Using the EasySep™ Human Bone Marrow CD138 Positive Selection Kit

The clinical specimens were evaluated using a panel of five common FISH probes detecting six genomic abnormalities: the Vysis IntelliFISH CCND1/IGH XT Probe Kit to detect the t(11;14) translocation, as well as probes to detect chromosome 5 (D5S23) or chromosome 15 polysomy (D15Z4) (single probe kit), MYC Breakapart, 13q deletion (D13S319), and TP53 deletion (D17Z1). Shown is the percentage of abnormal nuclei detected for each probe, which was higher following CD138+ cell enrichment with the EasySep™ Human Bone Marrow CD138 Positive Selection Kit. Note: Only specimens with an abnormal FISH signal pattern for each probe were included in the analysis.

Figure 3. EasySep™ Human Bone Marrow CD138 Positive Selection Kit Increases the Sensitivity of Chromosomal Abnormality Detection by FISH through CD138+ Cell Enrichment of Bone Marrow Specimens

In 14 out of 33 clinical bone marrow specimens analyzed by FISH, at least one genomic abnormality probed went undetected in unenriched specimens but was detected in CD138+ cell enriched specimens, demonstrating that plasma cell enrichment using the EasySep™ Human Bone Marrow CD138 Positive Selection Kit improves the sensitivity of FISH testing and can reduce the risk of false negative results. In the two representative patient bone marrow specimens analyzed above, CD138+ cell enrichment enabled the detection of chromosomal abnormalities that were not identified in unenriched specimens (blue boxes) and increased the frequency of abnormal nuclei detected when chromosomal abnormalities were detected in unenriched specimens.

Table 1. EasySep™ CD138 Reproducibility Study: Variability and Fold Enrichment Summary

A reproducibility study was performed to assess the variability of CD138+ cell enrichment achieved with the EasySep™ Human Bone Marrow CD138 Positive Selection Kit. The study was conducted with specimens of a given volume and initial CD138+ cell frequency across three independent laboratories and three unique kit lots. Contrived specimens were generated by spiking cells from the SK-MM-2 multiple myeloma cell line into whole blood samples from healthy donors at low (< 3%), medium (3 - 15%), and high (> 15%) CD138+ frequencies. CD138+ cells from 16 specimens were enriched using three unique lots of the EasySep™ Human Bone Marrow CD138 Positive Selection Kit over eight non-consecutive study days. Table 1 shows a statistical summary of the run-to-run or random error (Repeatability) variability, site-to-site (Between Site), lot-to-lot (Between Lot), overall (Reproducibility), and fold enrichment from the high, medium, and low CD138+ panel members. The low variabilities demonstrated that the performance of the EasySep™ Human Bone Marrow CD138 Positive Selection Kit is well controlled within lot (across site) and within site (across kit lot). CV = coefficient of variation.

Table 2. EasySep™ CD138 Precision Study: Statistical Summary of Repeatability and Within-Laboratory Precision Estimates

A precision study was performed to assess the repeatability and within-laboratory precision estimates in CD138+ cell enrichment; the study used one kit lot of the EasySep™ Human Bone Marrow CD138 Positive Selection Kit and specimens with a given volume and initial CD138+ cell frequency. The study was conducted using contrived specimens generated by spiking cells from the SK-MM-2 multiple myeloma cell line into bone marrow specimens collected from healthy donors at low (< 3%) and medium (3 - 15%) CD138+ frequencies. A total of six contrived specimens (three medium and three low) were tested on three non-consecutive study days. CD138+ cells from each specimen were enriched using a single kit lot of the EasySep™ Human Bone Marrow CD138 Positive Selection Kit across 12 replicates (four replicates per run, three runs in total). Table 2 shows a statistical summary of the repeatability (within-run) and within-laboratory (across-runs) precision estimates for purity, measured by flow cytometry. The low CV values demonstrate that the variability in the enriched CD138+ cell purity is well controlled within and across runs.