CSF free light chain identification of demyelinating disease: comparison with oligoclonal banding and other CSF indexes.

BACKGROUND: Cerebrospinal fluid (CSF) used in immunoglobulin gamma (IgG) index testing and oligoclonal bands (OCBs) are common laboratory tests used in the diagnosis of multiple sclerosis. The measurement of CSF free light chains (FLC) could pose as an alternative to the labor-intensive isoelectric-focusing (IEF) gels used for OCBs. METHODS: A total of 325 residual paired CSF and serum specimens were obtained after physician-ordered OCB IEF testing. CSF kappa (cKFLC) and lambda FLC (cLFLC), albumin and total IgG were measured. Calculations were performed based on combinations of analytes: CSF sum of kappa and lambda ([cKFLC+cLFLC]), kappa-index (K-index) ([cKFLC/sKFLC]/[CSF albumin/serum albumin]), kappa intrathecal fraction (KFLCIF) {([cKFLC/sKFLC]-[0.9358×CSF albumin/serum albumin]^[0.6687×sKFLC]/cKFLC)} and IgG-index ([CSF IgG/CSF albumin]/[serum IgG/serum albumin]). RESULTS: Patients were categorized as: demyelination (n=67), autoimmunity (n=53), non-inflammatory (n=50), inflammation (n=38), degeneration (n=28), peripheral neuropathy (n=24), infection (n=13), cancer (n=11), neuromyelitis optica (n=10) and others (n=31). cKFLC measurement used alone at a cutoff of 0.0611 mg/dL showed >90% agreement to OCBs, similar or better performance than all other calculations, reducing the number of analytes and variables. When cases of demyelinating disease were reviewed, cKFLC measurements showed 86% clinical sensitivity/77% specificity. CONCLUSIONS: cKFLC alone demonstrates comparable performance to OCBs along with increased sensitivity for demyelinating diseases. Replacing OCB with cKFLC would alleviate the need for serum and CSF IgG and albumin and calculated conversions. cKFLC can overcome challenges associated with performance, interpretation, and cost of traditional OCBs, reducing costs and maintaining sensitivity and specificity supporting MS diagnosis.

The effects of intrathecal rituximab on biomarkers in multiple sclerosis.

OBJECTIVES: Clinical trials of IV-rituximab have proved successful. It is unclear whether intrathecal (IT)-rituximab is more efficacious at lower doses. We examine its effects on B-cell biomarkers. METHODS: MS patients received IT-rituximab at 3 time-points. CSF and serum samples were obtained at up to 5 time-points (days 0, 7, 14, 56 and 112). Serum and CSF BAFF and CXCL13, and CSF kappa and lambda free light chains (FLC) were measured. Flow cytometry was performed, examining effects on lymphocytes, CD3-19+ and CD3-20+ cells. RESULTS: CSF BAFF fell following rituximab (p=0.0091 absolute values, p=0.0284 change from baseline) whilst serum BAFF increased across time-points 1-4 (p=0.0005 absolute values, p=0.0017 change from baseline). There were significant reductions in CD20+ and CD19+ cells in blood from baseline (p<0.0001) but not in CSF. CSF kappa FLC levels significantly increased (p=0.0480). CONCLUSIONS: BAFF levels fall in CSF but increase in serum following IT-rituximab. Rituximab appears to act peripherally with dramatic decreases in peripheral CD20+ and CD19+ cells. It is likely that CSF B-cell counts were too low to enable differences to be seen. The rapid reduction in B-cells suggests rituximab has immediate effects. The profound depletion of B-cells, despite low doses of rituximab, underlines rituximab's efficacy.

Measurement of free light chains with assays based on monoclonal antibodies.

Recently, serum free light chain (FLC) assays incorporating anti-kappa (κ) and anti-lambda (λ) FLC monoclonal antibodies have become available: N Latex FLC assay (Siemens) and Seralite® (Abingdon Health). The purpose of this review is to provide an overview of these two new monoclonal antibody-based methods. In doing so, the review will outline the performance characteristics of each method, including a summary of: assay principles, antibody specificity, analytical performance and assay performance in disease. Additionally, the review will describe the potential user benefits of adopting these new generation FLC assays, which are designed to overcome the established limitations of existing polyclonal antibody based FLC assays.

Central nervous system multiple myeloma--potential roles for intrathecal therapy and measurement of cerebrospinal fluid light chains.

Central nervous system (CNS) multiple myeloma (MM) is exceedingly rare and portends a dismal prognosis. While immunomodulators have contributed to the improvement in survival in MM, they appear to have limited activity against CNS MM and, paradoxically, may contribute to the evolution of resistant MM clones capable of surviving within the CNS. We undertook a retrospective analysis to characterize the features of CNS MM and outcome in 17 patients from four institutions identified between 2000 and 2011. The median age was 58 years. Patients had received a median of three prior therapies and all had been exposed to at least one of the so-called novel anti-MM agents before the diagnosis of CNS MM. The median time to CNS disease from initial diagnosis was 36 months. Cerebrospinal fluid (CSF) light chain measurements produced discrepant results to serum light chain measurements in some patients. Treatments included systemic pharmacotherapy, intrathecal (IT) chemotherapy and/or radiotherapy (RT). The median overall survival (OS) from diagnosis of CNS MM was only 4 months. OS was significantly better in patients who received IT chemotherapy (20 months vs. 2 months, respectively; P < 0.02). We conclude that the systematic evaluation of IT therapy and diagnostic utility of CSF light chain measurements in CNS MM are warranted.

Detection of free immunoglobulin light chains in cerebrospinal fluids of patients with central nervous system lymphomas.

Diagnosis of central nervous system (CNS) lymphoma depends on histopathology of brain biopsies, because no reliable disease marker in the cerebrospinal fluid (CSF) has been identified yet. B-cell lymphomas such as CNS lymphomas are clonally restricted and express either kappa or lambda immunoglobulin light chains. The aim of this study was to find out a potential diagnostic value of free immunoglobulin light chains released into the CSF of CNS lymphoma patients. Kappa (kappa) and lambda (lambda) free immunoglobulin light chains (FLC) were measured in CSF and serum samples collected from 21 patients with primary and secondary CNS lymphomas and 14 control patients with different neurologic disorders. FLC concentrations and ratios were compared between patient groups and were further analyzed in correlation with clinical, cytopathological, and radiological findings. FLC concentrations for all patients were lower in CSF when compared to serum. In patients with CNS lymphoma, the FLC ratios in CSF were higher (range 392-0.3) compared to control patients (range 3.0-0.3). Irrespective of cytopathological proven lymphomatous meningitis, in 11/21 lymphoma CSF samples the FLC ratios were markedly above 3.0 indicating a clonally restricted B-cell population. Increased FLC ratios in CSF were found in those patients showing subependymal lymphoma contact as detected in magnetic resonance imaging. In summary, this is the first report demonstrating that a significant proportion of patients with CNS lymphomas display a markedly increased FLC ratio in the CSF.

Assessment of free light chains in the cerebrospinal fluid of patients with lymphomatous meningitis - a pilot study.

BACKGROUND: Lymphomatous meningitis (LM) represents a severe complication of malignant lymphomas. While clinical suspicion is raised by symptoms ranging from mild disturbances of sensation to severe pain or impaired consciousness, the definite diagnosis of LM is often difficult to obtain. Since B-cell lymphomas are clonally restricted to express either kappa or lambda immunoglobulin light chain, we hypothesised that analysis of free light chain (FLC) ratios might facilitate the diagnosis of LM. METHODS: Kappa and lambda FLC were measured using a novel nephelometric assay in cerebrospinal fluid (CSF) and serum from 17 patients. 5/17 suffered from LM as demonstrated by cytology, immunocytology, and/or imaging procedures. RESULTS: Measurement of FLC concentrations in CSF was achieved for all 17 patients. FLC levels in CSF were lower than serum FLC levels in samples for the same patient obtained at the same time (p < 0.01). CSF and serum FLC concentrations correlated weakly in all patients irrespective of LM status. Significantly more patients with cytopathologically and immunohistochemically proven LM displayed abnormal kappa/lambda FLC ratios in CSF compared to individuals with no LM (p < 0.01). CONCLUSION: This is the first report demonstrating that a significant proportion of LM patients display an abnormal kappa/lambda FLC ratio in the CSF.

Autoimmune autonomic failure in a patient with myeloma-associated Shy-Drager syndrome.

We report here the case of a patient with the Shy-Drager syndrome and multiple myeloma who had evidence consistent with a central neural autoimmune basis for sympathetic autonomic failure. Autonomic function testing showed no recordable peroneal skeletal muscle sympathoneural traffic, normal arterial norepinephrine (NE) spillover during supine rest and no increment in NE spillover during exposure to lower body negative pressure. The patient's cerebrospinal fluid and serum contained an immunoglobulin G that bound to rat locus ceruleus (LC) in an in vitro test system. The myeloma protein was of the lambda subtype and bound in the rat LC, without binding in the substantia nigra, as demonstrated with anti-lambda antiserum. Since in this case the monoclonal antibody produced by the myeloma bound specifically to LC cells, the results are consistent with the hypothesis that in this patient the Shy-Drager syndrome may have had an immune-mediated basis.

IgA producing primary intracerebral lymphoma.

The first case of a primary and solitary IgA (lambda) producing tumour (possibly a non-Hodgkin's lymphoma) in the CNS is reported. Clinical and neuroimaging findings are described. Early diagnosis without brain biopsy and successful therapy were possible by CSF and serum immunoglobulin analysis which proved local paraprotein production restricted to the CNS.

Central nervous system expression of a monoclonal paraprotein in a chronic lymphocytic leukemia patient.

An unusual complication of chronic lymphocytic leukemia (CLL) is reported. The patient, a 79-year-old man, had a long standing history of CLL, that had been complicated by the development of a Guillain-Barré-like syndrome and a peripheral biclonal gammopathy. The biclonal immunoglobulins identified in the serum were IgM lambda and IgG lambda. The patient's condition progressed and he eventually developed ophthalmologic complications. Cerebrospinal fluid (CSF) obtained during evaluation of his visual dysfunction contained numerous small, mature lymphocytes consistent with the presence of CLL cells in the central nervous system (CNS); immunoperoxidase staining of these cells revealed a monoclonal population. Protein electrophoretic evaluation of the patient's CSF showed a single monoclonal band and immunofixation electrophoresis of the CSF revealed that the immunoglobulin present was IgG lambda. No evidence for the monoclonal IgM paraprotein identified in serum could be appreciated in the CSF by immunofixation. Taken together, these findings strongly implied that there was CNS involvement by the leukemia and this process caused the patient's neurologic symptoms. Furthermore, this study demonstrates that chronic lymphocytic leukemia should also be considered as one of the hematopoietic malignancies associated with monoclonal gammopathies involving the CNS.

Sensitive competitive-binding ELISAs for quantifying free kappa and lambda light chains in cerebrospinal fluid.

Simple, sensitive, and fully standardized solid-phase enzyme-linked competitive binding immunoassays to quantify free kappa and lambda immunoglobulin light chains are described. The assays were developed to measure the concentration of free light chains in cerebrospinal fluid (CSF), in part because elevated levels of free kappa light chains have utility as a diagnostic marker for multiple sclerosis (MS). Polyclonal rabbit antibodies raised against pooled Bence Jones proteins are bound to solid-phase Staphylococcal protein A and used as the primary antisera in this assay. A pool of Bence Jones proteins isolated from the urine of 10 individuals with multiple myeloma are used as a biotin-labeled ligand and to develop a standard curve. The assays as described are sensitive to the low nanogram range and are specific for free kappa or lambda light chains. The assays were found to have acceptable precision, and results correlated highly with concentrations determined using competitive-binding radioimmunoassays previously described.

Evidence for the presence of lambda chain dimers in cerebrospinal fluid of patients suffering from subacute sclerosing panencephalitis.

The presence of free lambda chain dimers in the CSF of selected patients suffering from subacute sclerosing panencephalitis was proved by use of agar double diffusion and immunoelectrophoresis. The significance of this finding is discussed.