Flow cytometric expression of CD71, CD81, CD44 and CD39 in B cell lymphoma.

Flow cytometry is a useful ancillary tool for the diagnosis of nodal B cell lymphomas. Well-established antigens have diagnostic limitations. This study aimed to assess the expression of CD71, CD81, CD44 and CD39 by flow cytometry in B cell lymphomas. Expression of these 4 antigens was queried in 185 samples with a diagnosis of a B cell lymphoma according to a histological examination of the lymph node and the World Health Organization (WHO) classification (follicular lymphoma [FL, n = 96], diffuse large B cell lymphoma/High grade B cell lymphoma [DLBCL/HGBH, n = 48], marginal zone lymphoma/lymphoplasmacytic lymphoma [MZL/LPL, n = 14], chronic lymphocytic leukemia/small lymphocytic lymphoma [CLL, n = 10], mantle cell lymphoma [MCL, n = 11], Burkitt lymphoma [BL, n = 4] and other [n = 2]). CD81 was bright and CD44 was dim in germinal center-derived malignancies, particularly aggressive lymphomas (BL and CD10-positive DLBCL/HGBL). CD81 was very dim in CLL. CD71 was bright in aggressive lymphomas (DLBCL/HGBL and BL). CD39 was bright in CD10-negative DLBCL. CD71 appeared valuable in the differential diagnosis between indolent and aggressive lymphomas, CD39 between CD10-negative DLBCL and MZL/LPL and CD81 between MCL and CLL. To conclude, we report the expression of CD71, CD81, CD44 and CD39 by FC in B cell lymphomas. Further studies will have to determine the value they add to specific FC panels.

Diagnostic performance of the ClearLLab 10C B cell tube.

INTRODUCTION: Pre-analytical and analytical errors can threaten the reliability of flow cytometry (FC) results. A potential solution to some of these is the use of dry, pre-mixed antibodies, such as the ClearLLab 10C system. The purpose of the present study was to compare the diagnostic performance of the ClearLLab 10C B cell tube with that of our standard laboratory practice. METHODS: We compared the diagnoses made with the ClearLLab 10C B cell tube (experimental strategy) with those made with standard laboratory practice (standard strategy). Samples were selected aiming for representation of the full spectrum of B cell disorders, with an emphasis on mature B cell malignancies, as well as healthy controls. RESULTS: We included 116 samples (34 normal controls, 4 acute lymphoblastic leukemias, 54 mature lymphoproliferative disorders in peripheral blood and bone marrow, 3 myelomas, 6 bone marrow samples with involvement by lymphoma and 1 with elevated hematogone count, 14 lymph node samples, 1 cerebrospinal fluid, and 1 pleural effusion). There were two diagnostic errors (1.7%). The agreement between the two strategies in the percentage of CD19 cells and fluorescence intensity of CD5, CD19, CD20, CD200, and CD10 was very good. CONCLUSIONS: In this study, the ClearLLab 10C B cell tube performed similarly to our standard laboratory practice to diagnose and classify mature B cell malignancies.

FMOD expression in whole blood aids in distinguishing between chronic lymphocytic leukemia and other leukemic lymphoproliferative disorders. A pilot study.

BACKGROUND: Within the hematopoietic compartment, fibromodulin (FMOD) is almost exclusively expressed in chronic lymphocytic leukemia (CLL) lymphocytes. We set out to determine whether FMOD could be of help in diagnosing borderline lymphoproliferative disorders (LPD). METHODS: We established 3 flow cytometry-defined groups (CLL [n = 65], borderline LPD [n = 28], broadly defined as those with CLLflow score between 35 and -20 or discordant CD43 and CLLflow, and non-CLL LPD [n = 40]). FMOD expression levels were determined by standard RT-PCR in whole-blood samples. Patients were included regardless of lymphocyte count but with tumor burden ≥40%. RESULTS: FMOD expression levels distinguished between CLL (median 98.5, interquartile range [IQR] 37.8-195.1) and non-CLL LPD (median 0.012, IQR 0.003-0.033) with a sensitivity and specificity of 1. Most borderline LPDs were CD5/CD23/CD200-positive with no loss of B-cell antigens and negative or partial expression of CD43. 16/22 patients with available cytogenetic analysis showed trisomy 12. In 25/28 (89%) of these patients, FMOD expression levels fell between CLL and non-CLL (median 3.58, IQR 1.06-6.21). DISCUSSION: This study could suggest that borderline LPDs may constitute a distinct group laying in the biological spectrum of chronic leukemic LPDs. Future studies will have to confirm these results with other biological data. Quantification of FMOD can potentially be of help in the diagnosis of phenotypically complex LPDs.