An approach for diagnosing plasma cell myeloma by three-color flow cytometry based on kappa/lambda ratios of CD38-gated CD138+ cells

Abstract

BackgroundWorld Health Organization (WHO) criteria are commonly used to diagnose plasma cell myeloma (PCM); however, these criteria are complex and require several laboratory parameters. For differentiating reactive plasmacytosis from clonal plasma cell (PC) neoplasms such as PCM, it is important to accurately determine the expression of cytoplasmic immunoglobulin light chains.MethodsWe retrospectively analyzed the records of 27 selected patients with PCM who underwent bone biopsies for confirmative diagnosis according to WHO criteria. Twenty-three controls were also investigated. In the present study, all the samples were analyzed using flow cytometry (FC) in the side scatter vs. CD38 histogram mode, and the CD38-gated PC population was identified. Bivariate histograms of CD138/kappa and CD138/lambda were assessed, and the ratios of dual-positive cells to the CD138+ PC population were calculated. The kappa/lambda ratio was defined as the ratio of CD138/kappa to CD138/lambda.ResultsPCM cells were distinguished from normal PCs using cutoff levels between 0.76 and 1.5, at a sensitivity of 96.3% and specificity of 95.7%.ConclusionsThree-color FC analysis is simple to perform and inexpensive, with clinically relevant data obtained soon after the completion of FC measurements. The detection of the cytoplasmic kappa/lambda ratio of CD38-gated CD138+ PCs may be a useful tool in the diagnosis of PCM. To the best of our knowledge, this report represents the first diagnostic assessment of the cytoplasmic kappa/lambda ratio in CD38-gated CD138+ PCs using FC analysis. This method may help in more simple, efficient, rapid, and accurate diagnosis of PCM.Virtual slidesThe virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1568085959771735

Cell Surface-Associated Anti-MUC1-Derived Signal Peptide Antibodies: Implications for Cancer Diagnostics and Therapy

“…3 ). A similar selection analysis of PC from BM aspirate of MM patients, based upon kappa/lambda and CD138 expression, was recently described by Nakayama et al [45] and confirmed the rationale of our analysis. The analysis also revealed positive MUC1 expression in a small population of CD138-negative cells.…”

Flow cytometric immunophenotyping of plasma cells across the spectrum of plasma cell proliferative disorders: A fresh insight with pattern‐based recognition

“…Thus, demonstration of altered ratio of kappa and lambda expressing PC is essential for demonstrating cyLCR in cases with all APC or all NPC, based on IMWG criteria, cyLCR has been defined as a cyKLR >4.0 or <0.5. Nakayama et al (2012) showed that a cyKLR of <0.76 and >1.5 has a sensitivity of 96.3% and a specificity of 95.7% and similarly, van Zaanen et al (1995), showed cyKLR of >3 and <0.48 has 100% sensitivity and 97.8% specificity to differentiate MM patients from reactive plasmacytosis. When we assessed the cyKLR in 462 samples with both APC and NPC, we found that the ratio was within the reference range (0.26–3.98) in substantial number of samples (Tables 3 and 4).…”

Automated and simplified identification of normal and abnormal plasma cells in Multiple Myeloma by flow cytometry

“…The Euro-Flow method, which is considered the standard method for MRD assessment by flow cytometry, is composed of an 8-color panel with a common core (CD38, CD138, CD45, and CD19) and eight markers divided in two tubes (CD56/beta-2-microglobulin/kappa/lambda and CD27/CD28/CD81/CD117) (12). Specifically, they first gated cells on the SSC/CD38 dimensions and then selected PC on the kappa/CD138 and lambda/CD138 dimensions (29). In our simpler smart antibody panel, we decided to remove the CD138 marker given its lability after sampling (27,28) and to use CD38, kappa and lambda light-chain, instead of CD38 and CD45, to select total PC.…”

“…Nakayama and colleagues employed a similar strategy to select PC in samples from patients with MM at diagnosis. Specifically, they first gated cells on the SSC/CD38 dimensions and then selected PC on the kappa/CD138 and lambda/CD138 dimensions (29). These three markers allow a better and clearer distinction of PC than the use of CD38 and CD45 (Fig.…”