Comparison of polyclonal and monoclonal antibody based free light chain assays taking account of renal function

Abstracts smoldering MM (SMM). Samples from patients with MGUS and healthy donors were also included in the study. LEN treatment was performed at concentration ranging from 0,1 to 2 M during all the differentiation culture period. Moreover moDC differentiation was performed in the presence of CM of human TERT transfected-hMSCs (hTERT-hMSCs) treated for 5 days with LEN. DC maturation markers (CD83, HLA-DR, CD80, CD86 and CD209) were evaluated by flow cytometry. The levels of soluble factors produced by mo-DCs were measured in the conditioned media (CM) of mo-DC by a Bio-PlexÒ Multiplex System. The expression levels of Ikaros and Aiolos were also evaluated by western blot. LEN treatment induced a reduction of both number and % of mature mo-DC as compared to untreated controls. On the other hand, LEN treatment significantly increased the median intensity expression of CD86 HLA-DR and CD209 but not of CD80 by moDCs derived from BM. Similarly increased CD209 expression has been also seen in mo-DCs derived from PB in both MM and SMM patients. LEN treatment enhanced the production of IL-8 and MCP1 and decreased TNF- levels. Ikaros mediated the effect of LEN on DCs as we observed a significant down-regulation of Ikaros levels in THP1-DCs after LEN treatment with a dose dependent effect. On the other hand, we found that LEN blunted the inhibitory effect of hTERT-hMSCs on mo-DC differentiation in three independent experiments and slightly down-regulated IL-6 and IDO but not TGFB1, IL-8, TNF and HGF gene expression. The effect of LEN on the immunomodulatory properties of hMSC was likely to be not mediated by Ikaros or Aiolos because both transcription factors were not expressed by hMSCs. These evidences underline a possible new effect of IMiDsÒ on the alloreactivity against MM cells.

PO-294 Comparison of polyclonal and monoclonal antibody based free light chain assays taking account of renal function O. Decaux,1 C. Moreau,2 B. Autier,2 L. Peltier,2 M. Escoffre,3 T. Lamy,3 M. Sebillot,1 C. Bendavid,2 L. Guenet,2 B. Grosbois1 1

Internal medicine, Rennes University Hospital, 16, boulevard de

Bulgarie, 35200 Rennes, France; 2Biochemistry, Rennes University Hospital, 2 rue Henri Le Guilloux, 35000 Rennes, France; 3Clinical Hematology, Rennes University Hospital, 2 rue Henri Le Guilloux, 35000 Rennes, France

Introduction: Serum free light chain (FLC) assay is an increasingly important method in diagnostic and follow-up approaches of monoclonal gammopathies. Since 2011, two immunonephelometric assays are available: the FreeliteTM assay (The Binding Site, UK) using polyclonal antibodies, and the N Latex FLC assay (Siemens, Germany) using monoclonal antibodies. While Hutchison highlighted extended reference range for the/ratio obtained with the FreeliteTM assay for patients with renal impairment (CKD-EPI<60ml/min), no modification is observed for the N Latex FLC assay as reported by Jacobs in 2014. Recent publications

reported lack of correlation and few discrepancies between the 2 assays. The aim of this study was to assess clinical agreement and biological correlation between the 2 assays taking account of the renal function (CKD-EPI). Methods: Between July 2012 and December 2013, serum FLC of patients followed-up or screened at the laboratory of the hospital for monoclonal gammopathy were quantified with both FreeliteTM and N Latex FLC assays. The corelation between the two assays was studied taking account of the renal function evaluated by CKD-EPI. Results: The analysis of the 817 sera of 455 patients showed that agreement was lost for values under 7 mg/l and over 50-150 mg/l (function of the type of FLC) but without link to renal function. Deming regressions had similar profiles for each group of CKD-EPI and correlation was not affected by renal function (no significant differences between Pearson’s r, p>0.390). The analysis of qualitative results showed independence between proportion of discrepancies and renal function (p¼0.639 in case of use of the extended reference ranges for the FreeliteTM assay), which is not improved by consideration of the technical assay variability (p¼0.270). In all, the results showed that the lack of correlation and the discrepancies for 7.6% of patients are observed for extremely high and low values, but without relationship to the renal function. Conclusion: Our results confirm good agreement between the 2 tests which are both reliable and robust. Renal failure has no impact on the correlation between the two tests. However we observed few discordant results which emphasize the need to analyse the results of FLC tests in conjunction with the results of traditional tests and clinical evolution.

PO-295 Structural characterisation of immunoglobulin G glycosylation in multiple myeloma G.N. Le, S. Mittermayr, C. Walsh, K.R. Ting, L. James, J. Bones, P. O’Gorman 1

The Mater Misericordiae University Hospital; 2The National Institute

for Bioprocessing Research and Training

Introduction: Multiple myeloma(MM) is an incurable plasma cell malignancy, with eventual disease refractory and relapse. Its benign precursor, monoclonal gammopathy of undetermined significance(MGUS), has an annual transformation rate of 1%, while that of the asymptomatic smouldering myeloma(SMM) is 10%. The pathognomonic feature is the presence abnormal monoclonal immunoglobulin, of which immunoglobulin G(IgG) paraprotein is the most common. All subclasses of Igs are post-translationally modified by adding N-glycans, reportedly influencing structure, stability, and biological function. Previous studies in MM IgG suggested an increase in the glycosylation of the antigen-binding fragment (Fab), and an overall elevation of sialylation. Using glycoproteomic platforms, we aimed to investigate and characterise the IgG N-glycosylation profiles across the myeloma disease spectrum. Material/Methods: Serum samples were collected from patients with MGUS(n¼7), SMM(n¼6), newly-diagnosed MM(n¼7) and age-matched healthy controls(n¼5). N-glycans were enzymatically liberated from purified IgG and profiled using hydrophilic-

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