Monoclonal free light chain detection and quantification: Performances and limits of available laboratory assays.

The detection and quantification of immunoglobulin free light chains in serum and urine is recommended for the diagnosis and monitoring of monoclonal gammopathies according to the guidelines of the International Myeloma Working Group (IMWG). Several tests are currently available in the clinical laboratory to detect and quantify free light chains but although quality, efficiency, and effectiveness have been improved, the results are still variable and poorly harmonized and standardized. The present review article wants to analyze these aspects, with a keen eye on techniques, such as mass spectrometry, that could replace in the practical clinical laboratory the current methods including Bence-Jones protein assay and free light chain immunoassays.

Polymethylmethacrylate membrane and serum free light chain removal: enhancing adsorption properties.

INTRODUCTION: Polymethylmethacrylate (PMMA) membranes can adsorb a wide variety of uremic toxins including serum free light chains (sFLC). However, limited data are available regarding the clinical use of PMMA in multiple myeloma patients and its maximum adsorption capacity in this setting. AIM: This study aimed to measure the capacity of PMMA to adsorb sFLC and identify strategies to improve its efficiency in clinical practice. METHODS: Ten patients with dialysis-dependent renal failure and high levels of sFLC were included in the study. Five patients received standard PMMA hemodialysis (HD; n = 18), while in the other 5 patients a new technique called enhanced adsorption dialysis (EAD) was used, which involves PMMA dialyzer replacement after 2 h (n = 19). In all patients, sFLC were measured at the beginning and at the end of each dialysis session to calculate the difference between start and end of treatment and the percentage removal. RESULTS: PMMA membranes reduced sFLC in both the PMMA HD and EAD groups. PMMA HD showed similar efficiency on κ and λ percentage removal (22.3 and 21.0%, respectively, n.s.) but, in contrast, had a significantly greater effect on the delta of sFLC in κ [1,555 mg/l (-511 to +6,027)] versus λ [390 mg/l (120-650)] treatments (p = 0.007). EAD treatments only partially increased percentage removal of κ sFLC (22.3-31.0%, p = 0.38), while they had a significantly great effect on λ (21.0-53.1%, p = 0.003). A positive linear correlation was found between delta sFLC and pre-HD sFLC concentrations in PMMA HD κ treatments (r = 0.68, p < 0.02) but not for λ treatments (r = 0.54, p = 0.21), while the analysis of patients receiving EAD demonstrated a strong positive correlation for both κ and λ subtypes (r = 0.81 and r = 0.85, respectively, p < 0.008). In EAD sessions, a positive linear correlation was shown between blood flow during treatment and percentage removal of sFLC (r = 0.58, p = 0.02); however, with PMMA HD such a correlation was not observed (r = 0.28, p = 0.25). CONCLUSIONS: PMMA membranes can efficiently adsorb sFLC, but the process is limited by membrane saturation and is different between κ and λ sFLC. The new EAD technique can greatly improve λ removal but only partially act on κ sFLC. Therefore, EAD should be considered a valid economic treatment option without side effects in particular subsets of patients for the removal of sFLC.

Granulocytic-macrophagic and macrophagic colony stimulating factors elicit colonies of mast cells in mouse bone marrow agar culture. An electron microscope study.

Granulocytic-macrophagic colony stimulating factor (GM-CSF) and macrophagic colony stimulating factor (M-CSF or CSF-1) stimulate bone marrow cells of mouse to produce in semisolid agar colonies in which mononuclear cells were reported to be macrophages. We verified in such colonies the ultrastructure of the mononuclear cells which had cytoplasmic granules of the mast cells and lacked lysosomes, therefore we considered them as mast cells. However, the granules content did not reach the degree of condensation typically found in granules of mouse peritoneal mature mast cells. The mast cells of colonies obtained in agar can be mast cells arrested at some point in the maturative process, mast cells of a yet unrecognized type or cells with mast cells ultrastructural features which behave as precursors for cells of myeloid lineage.

Inefficacy of moving average algorithm as principal quality control procedure on Technicon System H6000.

Bull's algorithm, in its "revisited" formulation, represents one of the main quality control (QC) procedures in several multichannel automatic hematological analyzers. Its efficacy, however, is reduced in the theoretical event that red blood cells (RBC) and hemoglobin (Hgb) undergo a concomitant analytical drift while mean corpuscular volume (MCV) remains unaffected, so that a null effect is registered on the related erythrocytic indices: mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC). This particular phenomenon has been observed on the Technicon System H6000. Routine daily work was kept in control through the use of commercial controls and fresh blood samples: a reproducible positive drift of two directly measured erythrocytic parameters (RBC and Hgb) and of the calculated hematocrit (Hct) was observed proportional to the time of continuous use of the instrument. The usefulness of Bull's QC scheme was greatly reduced: it failed to detect "out of control" situation in 38%, 15%, and 13% of cases in the monitoring of MCV, MCH, and MCHC, respectively, when compared with the traditional 2 SD limits on QC samples.