The optimized anti-CD20 monoclonal antibody ublituximab bypasses natural killer phenotypic features in Waldenstr?m macroglobulinemia | Haematologica

摘要

Waldenstr?m macroglobulinemia (WM) is a rare form of lymphoma characterized by an infiltration of lymphoplasmacytic cells in bone marrow and immunoglobulin M monoclonal gammopathy.1 Despite the introduction of several therapeutic approaches, WM remains incurable.2 Therefore, a better understanding of the mechanisms underlying the immune surveillance around this pathology is still needed to help to develop novel treatment strategies. Natural killer (NK) cells were initially identified through their ability to lyse tumor cells. They express an array of inhibitory, activating, adhesion and cytokine receptors that enable them to kill targets while sparing normal cells.3 NK cells also express the low-affinity Fc receptor (FcγRIIIA/CD16), enabling them to detect antibody-coated target cells and to exert antibody-dependent cell cytotoxicity (ADCC).3 In this study, we focused our attention on NK cells relative to the presence of a circulating B-cell clone in WM patients.The 47 WM patients in the study were diagnosed at the WM French Reference Center Pitié-Salpêtrière Hospital, Paris, France, according to classical biological criteria.1 This study was approved by the institutional ethic committee at the Pitié-Salpêtrière Hospital (CPPIDF6) and all patients provided informed consent prior to participation.Characteristics of the WM patients are summarized in Table 1. They were untreated or had received no treatment during the two years prior to the study. Patients were compared to 20 healthy blood donors from the Etablissement Fran?ais du Sang. In 26 of 47 patients, circulating B-cell clone was detected with a frequency ranging from 0.7% to 63.0% of lymphocytes, corresponding to 0.1% to 17.0% of leukocytes. NK cells, and B and T lymphocytes from freshly harvested whole blood samples were analyzed on the CD45+ lymphocytic gate after staining with an appropriate antibody cocktail (Online Supplementary Appendix), as previously described.4,5 At least 100,000 leukocytes were analyzed on a FACSCanto II (BD Biosciences) to assess the distribution of NK cells, B and T lymphocytes from WM patients, relative to the presence of circulating B cells (as defined in the Online Supplementary Appendix), and compared with healthy controls. A similar absolute number of whole CD3+ T and CD19+ B cells in healthy controls and WM samples are observed (Figure 1A). The absolute value of B cells correlated significantly with the percentage of a circulating B-cell clone (Figure 1B). There was no difference in the distribution of CD3?CD56+ NK cells and both CD56dim and CD56bright subsets between the study groups (Figure 1C and D), indicating that WM does not disturb this immune subset, compared with other hematologic diseases.5–8View this table:View inlineView popupDownload powerpointTable 1. Main characteristics of WM patients.Download figureOpen in new tabDownload powerpointFigure 1. Distribution of lymphocyte subsets and characteristics of natural killer (NK) cells from Waldenstr?m macroglobulinemia (WM) patients with or without circulating B-cell clones. (A) Absolute values of CD3+ T and CD19+ B cells from peripheral blood. (B) Linear regression between absolute value of CD19+ B cells and the percentage of circulating B-cell clones (WM clone). (C) Absolute value and frequency of CD3?CD56+ NK cells from peripheral blood. (D) Expression of CD56bright gated on CD3?CD56+ NK cells. (E) Frequency and mean fluorescence intensity (MFI) of CD16 on CD3?CD56dim NK cells. (F) Frequency and absolute value of CD69 on CD3?CD56dim NK cells. (G) Frequency and absolute value of CD57 on CD3?CD56dim NK cells. (H) Frequency of NKp30 on CD3?CD56dim NK cells. Cells were collected from healthy donors (Ctl; circles) and WM patients without [(clone (?); squares) or with (clone (+); triangles)] circulating B-cell clones (WM clone). Horizontal bars represent median values. Intergroup comparisons were assessed with Kruskal Wallis test and Dunn post test; *P<0.05, **P<0.001, ***P<0.0001