| [Background and Aims]Multiple myeloma (MM) is one of malignant tumor characterized by accumulated malignant plasma cells which originated in the germinal center B cell, usually developed from monoclonal gammopathy of undetermined significance (MGUS). The laboratory examination methods used to MM clinical diagnosis mainly include the serum protein electrophoresis (SPE), immune fixation electrophoresis (IFE), capillary zone electrophoresis (CZE), urine Bence Jones protein determination, serum and urine of light chain immunoglobulin quantitative determination, etc., but due to the reasons such as the sensitivity and specificity, part of patients with MM cannot be checked out. In recent years, many clinical studies have shown that serum free light chain (sFLC) has a good application value in diagnosis, judgement of curative effect, and condition monitoring of MM and related diseases. International myeloma collaboration in the latest MM curative effect evaluation system has put the sFLC indicators as important standard of diagnosis and therapeutic evaluation in patients with MM, especially with widowed secretion and no secreted MM. This study plan to determine serum free kappa light chain and free lambda light chain level of the region healthy people and patients with MM by nephelometric assays in automatic immune turbidimetric apparatus, while calculate the serum free kappa light chain/free lambda light chain ratio, establish the normal reference range, explore the clinical significance in diagnosis, therapeutic evaluation, and condition monitoring, and provide a basis for the clinical diagnosis and treatment of MM.[Material and Methods]1. Object111inpatients and outpatients diagnosed MM in hematology department of the first affiliated hospital of Zhejiang University between May2012and May2013were included.30patients with other hematology diseases (primary AL amyloidosis, plasmacytoma, and monoclonal gamma immunoglobinopathy excluded),40patients with renal dysfunction (renal dysfunction caused by MM excluded), and36patients with other benign and malignant diseases were included as other diseases group, at the same time200physical examination peoples (normal liver function, renal function, blood cell count, and urine routine examination) were selected as normal control group. Combined with clinical data, the objects were divided into follow five groups:A, B, C, D,and E.Group A,111patients with MM (68male and43female; M:F,1.58:1; mean age,59.6y; standard deviation,10.6y) contained28IgA MM,68IgG MM,1IgM MM,1IgD MM,13light chain MM;58kappa MM, and53lambda MM (shown in table2.2). The diagnosis of111patients with MM and no other tumors merger conformed to MM diagnosis standard, primary AL amyloidosis, plasmacytoma, and monoclonal gammopathy were excluded.22patients were first diagnosed as MM and77patients with MM were in follow-up. Group B,30patients with other hematology diseases (14male and16female; mean age,53.3y; standard deviation,17.0y, primary AL amyloidosis, plasmacytoma, and monoclonal gamma immunoglobinopathy excluded) contained lymphoma, acute myeloid leukemia, chronic granulocyte leukemia, and iron deficiency anemia patients.Group C,40patients with renal dysfunction (22male and18female; mean age,54.8y; standard deviation,15.9y, renal dysfunction caused by MM excluded). Group D,36patients with other benign and malignant diseases (20male and16female; mean age,58.5y; standard deviation,15.7y). group E, normal control group,200physical examination peoples (104male and96female; mean age,42.7y; standard deviation,13.6y) with normal liver function, renal function, blood cell count, and urine routine examination.2. Experimental method(1) Serum specimen collection and preservation of patients with MM Venipunctures were performed in the morning following a12h fast before chemotherapy. All specimens of patients with MM (patients with follow-up included) were collected into three5ml promote coagulant vacutainers. Samples were sent to the laboratory after let stand for2h, centrifuged (10min,3000g),divided into EP tubes, and stored at-78℃.(2) Urine specimen collection and preservation of patients with MMThe2ml morning urine of patients with MM before chemotherapy (patients with follow-up included) were collected and centrifuged (10min,3000g),the supernatant were divided into EP tubes and stored at-78℃.(3) Specimen collection and preservation of other patients in group B, C, D, and E3ml fasting venous blood specimens of other patients were collected. After let stand for2h and centrifuged (10min,3000g), the serum were divided into EP tubes and stored at-78℃. (4) sFLC detectionSerum FLC levels were detected by BNII automatic immune turbidimetric instrument using the principle of timing nephelometric assays.(5) Serum immunoglobulin A, G, M (IgA, IgG, IgM) detectionSerum immunoglobulin A, G, M (IgA, IgG, IgM) levels were detected by BNII automatic immune turbidimetric instrument using the principle of timing nephelometric assays.(6) Serum light chain (kappa and Lambda light chain) and urine light chain (kappa and Lambda light chain) detectionSerum light chain (kappa and Lambda light chain) and urine light chain (kappa and Lambda light chain) levels were detected by IMMAGE800automatic immune turbidimetric instrument using the principle of rate nephelometric assays.(7) SPE detectionSPE were detected by Spife3000automatic agarose gel electrophoresis analyzer using cellulose acetate membrane as the support medium of electrophoresis.(8) Serum IFE detectionIFE were detected by Spife3000automatic agarose gel electrophoresis analyzer.(9) Statistical AnalysesAll relevant statistical analyses were performed using SPSS, version16.[Results]1. Serum k-FLC of200healthy control were5.60～31.75mg/L, λ-FLC were5.42～49.38mg/L, serum k-FLC/λ-FLC ratio were0.34～1.75, Serum k-FLC95%confidence interval (CI):6.08～25.40mg/L; Serum λ-FLC95%CI:7.66～32.70mg/L; and k-FLC/λ-FLC ratio95%CI:0.32～1.24. 2. There was no significant age and gender difference in serum FLC levels of200healthy control.3. serum k-FLC, λ-FLC, and serum k-FLC/λ-FLC ratio of111patients with MM were157.12.19±370.10,256.69±991.39,15.05±39.60respectively, and serum k-FLC, λ-FLC level, and serum k-FLC/λ-FLC ratio were significant difference compared with B, C, D, and E groups, there was no significant difference among B, C, D, and E groups.4. Serum FLC levels of22patients first diagnosed as MM were abnormal, IFE results of21patients were positive, SPE results of20patients were positive, serum light chain(Kappa and Lambda light chain) of20patients were abnormal, and urine light chain(Kappa and Lambda light chain) of18patients were abnormal.5.77patients with MM were in follow-up, curative effect evaluations of4patients with MM were complete response (CR),28patients were partial response (PR), and11patients were progressive disease (PD),35patients were stable disease (SD) At different time points of follow-up, serum k-FLC,λ-FLC, and serum k-FLC/λ-FLC ratio can well indicate condition changes of patients, especially serum kappa-k-FLC/λ-FLC ratio were highly consistent with changes.(Conclusion](1) The serum FLC had important significance in the clinical diagnosis of patients with MM, its sensitivity was higher than the serum IFE, SPE, serum light chain and urine light chain.(2) serum FLC can be used to the clinical curative effect evaluation and monitoring of patients with MM. |
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