Synthesis Of Free Light Chains Research Articles

Free Light Chains κ and λ as New Biomarkers of Selected Diseases.

Diagnostic and prognostic markers are necessary to help in patient diagnosis and the prediction of future clinical events or disease progression. As promising biomarkers of selected diseases, the free light chains (FLCs) κ and λ were considered. Measurements of FLCs are currently used in routine diagnostics of, for example, multiple myeloma, and the usefulness of FLCs as biomarkers of monoclonal gammopathies is well understood. Therefore, this review focuses on the studies concerning FLCs as new potential biomarkers of other disorders in which an inflammatory background has been observed. We performed a bibliometric review of studies indexed in MEDLINE to assess the clinical significance of FLCs. Altered levels of FLCs were observed both in diseases strongly connected with inflammation such as viral infections, tick-borne diseases or rheumatic disorders, and disorders that are moderately associated with immune system reactions, e.g., multiple sclerosis, diabetes, cardiovascular disorders and cancers. Increased concentrations of FLCs appear to be a useful prognostic marker in patients with multiple sclerosis or tick-borne encephalitis. Intensive synthesis of FLCs may also reflect the production of specific antibodies against pathogens such as SARS-CoV-2. Moreover, abnormal FLC concentrations might predict the development of diabetic kidney disease in patients with type 2 diabetes. Markedly elevated levels are also associated with increased risk of hospitalization and death in patients with cardiovascular disorders. Additionally, FLCs have been found to be increased in rheumatic diseases and have been related to disease activity. Furthermore, it has been suggested that inhibition of FLCs would reduce the progression of tumorigenesis in breast cancer or colitis-associated colon carcinogenesis. In conclusion, abnormal levels of κ and λ FLCs, as well as the ratio of κ:λ, are usually the result of disturbances in the synthesis of immunoglobulins as an effect of overactive inflammatory reactions. Therefore, it seems that κ and λ FLCs may be significant diagnostic and prognostic biomarkers of selected diseases. Moreover, the inhibition of FLCs appears to be a promising therapeutical target for the treatment of various disorders where inflammation plays an important role in the development or progression of the disease.

ASSAY OF IMMUNOGLOBULIN FREE LIGHT CHAINS IN THE SERUM FOR EVALUATING CHEMOTHERAPY EFFICACY IN PATIENTS SUFFERING FROM MULTIPLE MYELOMA WITH INTACT MEASURABLE PARAPROTEIN

Aim. To evaluate the concentration of immunoglobulin free light chains (FLC) in comparison with that of intact measurable paraproteins (PIg) in patients with relapsed/resistant multiple myeloma (RR MM) undergoing treatment with bortezomib.Materials and methods. A retrospective study included 15 patients with RR MM with intact measurable PIg. Following 6 cycles of bortezomib treatment, an evaluation of the treatment efficacy was performed using standard criteria and by analysing serum FLC of immunoglobulins (sFLC).Results. A partial response (PR) and small response was achieved in 4 and 5 patients, respectively. The stabilization of the disease was observed in 6 patients. No cases of complete response (CR) or stringent complete response (SCR) were recorded. On the basis of the data on the concentration of sFLC after treatment, all patients were divided into 2 groups: those with an abnormal (clonal) and normal κ/λ ratio. In 11 patients with a response lower than PR, sFLC κ/λ ratio was of a clonal nature, which corresponded to changes in the concentrations of intact PIg during treatment. In 4 cases with PR, the residual tumour was determined by the presence of intact PIg within the 32–45 % range under, however, a normal sFLC κ/λ ratio.Conclusion. Treatment with bortezomib affects all processes in MM with intact PIg, such as synthesis of FLC by tumour plasma cells, a decrease in the amount of circulating sFLC in blood and in the concentration of intact PIg. Normalization of sFLC κ/λ ratio under the achievement of PR could be considered as a prognostic factor in a favourable clinical outcome.

Intrathecal K free light chain synthesis in multiple sclerosis at clinical onset associates with local IgG production and improves the diagnostic value of cerebrospinal fluid examination

Background. The pathological significance and the diagnostic usefulness of intrathecal κ and λ free light chain (FLC) synthesis in Multiple Sclerosis (MS) are debated. Methods. Paired cerebrospinal fluid (CSF) and serum specimens from 70 relapsing remitting MS (RRMS), 40 with and 30 without CSF restricted IgG Oligoclonal Band (IgGOB), and 37 from healthy controls (HC) were analyzed. IgG, IgM, κFLC and λFLC concentrations and indexes were evaluated. All RRMS performed MRI to estimate white and grey matter (WM) pathology. Results. In HC, no intrathecal κ or λ FLC synthesis was found, and κFLC and λFLC Indexes were reciprocally correlated (r = 0.67, p < 0.001). In RRMS, intrathecal κFLC or λFLC synthesis was demonstrated in respectively 66% and 43% of the cases, the Qκ/λ ratio was significantly higher compared to HC (17.0 ± 31.3 vs 0.79 ± 0.20, p < 0.001) and the correlation between κFLC Index and λFLC Index was weak (r:0.38, p < 0.05). Intrathecal IgG synthesis was associated with κFLC Index (IgG Index: r2 = 0.53, β = 0.73, p < 0.001; IgGLOC: r2 = 0.37, β = 0.61, p < 0.001; IgGIF: r2 = 0.69, β = 0.83, p < 0.001), but not with λFLC Index, while intrathecal IgM synthesis correlated with λFLC Index (IgM Index: r = 0.41, p < 0.001; IgMLOC: r = 0.34, p < 0.005; IgMIF: r = 0.45, p < 0.001), but not with κFLC Index. 26% of RRMS patients without CSF-restricted IgGOB had increased κFLCLOC. Finally, no associations were observed between any CSF and MRI parameters. Conclusions. The demonstration of intrathecal κFLC synthesis may further improve the diagnostic usefulness of CSF examination in RRMS. The marked increased in Qκ/λ further suggests a deregulated B-cell activation in MS pathology.

The Role of Assay of Free Immunoglobulin Light Chains in the Diagnosis of the Onset of Multiple Sclerosis

Objective. To assess the diagnostic value of assaying immunoglobulin (IgG) light chains at the onset of multiple sclerosis (MS). Materials and methods. A total of 226 patients took part in the study; group 1 (n = 111) were patients with clinically isolated syndrome (CIS) with development to MS within the first two years; group 2 (n = 49) were patients with CIS who did not progress to MS in the first two years; group 3 (n = 20) consisted of patients with inflammatory diseases of the central nervous system. The reference group (group 4, n = 46) consisted of patients with noninflammatory CNS diseases. The following immunological indicators were assessed in the patients: the clonal nature of cerebrospinal fluid (CSF) IgG and the concentrations of free ϰ and λ light chains in the CSF and their ratio. Results. Synthesis of free light chains was significantly greater in group 1 than groups 2 and 4. Free light chain synthesis in group 3 was significantly greater than that in groups 2 and 4 but was not significantly different from that in group 1. Free light chain production was significantly greater in patients with oligoclonal IgG synthesis than in patients without oligoclonal synthesis. The level of production of free light chains in patients of group 1 was significantly greater than that in group 2, regardless of whether or not oligoclonal IgG was produced. The most valuable diagnostic markers were the concentration and the coefficient of CSF:serum concentrations of κ light chains. Use of these parameters along with assessment of the clonality of IgG synthesis produced a 50% reduction in number of false negative results. Independently of other factors, increases in κ chain levels led to a 9.718-fold increase in the probability of a diagnosis of MS. Conclusions. Assay of free light chains as a lab marker increases the accuracy of diagnoses of MS and provides an indirect evaluation of the risk that CIS will progress to complete MS in the next two years.

Prognostic value of free light chains lambda and kappa in early multiple sclerosis

Background: Cerebrospinal fluid (CSF) immunoglobulin free light chains (FLC) have been suggested as quantitative alternative to oligoclonal bands (OCB) in the diagnosis of multiple sclerosis (MS). However, little is known on their role in predicting clinical and paraclinical disease progression, particularly in early stages. Objective: To assess the prognostic value of FLC in OCB-positive patients with clinically isolated syndrome (CIS) suggestive of MS and early MS. Methods: We determined FLC kappa (KFLC) and lambda (LFLC) in CSF and serum by nephelometry in 61 patients (CIS (n = 48), relapsing-remitting multiple sclerosis (n = 13)) and 60 non-inflammatory neurological controls. Median clinical follow-up time in CIS was 4.8 years (interquartile range (IQR), 1.5–6.5 years). Patients underwent 3T magnetic resonance imaging (MRI) at baseline and follow-up (median time interval, 2.2 years; IQR, 1.0–3.7 years) to determine T2 lesion load (T2LL) and percent brain volume change (PBVC). Results: CSF FLC were significantly increased in CIS/MS compared to controls (all p < 0.001). A lower KFLC/LFLC CSF ratio was associated with CIS-clinically definite multiple sclerosis (CDMS) conversion (hazard ratio (HR) = 2.89; 95% confidence interval (CI) = 1.17–7.14; p < 0.05). No correlations were found for FLC variables with T2LL or PBVC. Conclusion: Our study confirms increased intrathecal synthesis of FLC in CIS/MS which supports their diagnostic contribution. The KFLC/LFLC CSF ratio appears to have a prognostic value in CIS beyond OCB.

Comparison of the free and total light chain assays in serum and urine samples with immunofixation electrophoresis for detecting monoclonal proteins in patients with monoclonal gammopathy

ABSTRACT Monoclonal protein (M-protein) is produced by a malignant clone of plasma cells. Detected in serum and/or urine, this typically indicates multiple myeloma (MM) or other monoclonal gammopathy (MG). In a majority of MM cases, with the production of intact monoclonal immunoglobulin (Ig), malignant plasmocytes and/or B lymphocytes often produce excessive amounts of free light chains (FLCs). Excessive synthesis of FLCs lowers the ability of renal proximal tubules to re-absorb FLCs, which results in abnormally high levels of FLCs in the urine (Bence Jones protein, BJP). In laboratory practice, there are tests available for the quantitative measurement of only FLCs κ and λ or for total light chains (TLCs). These tests measure both free forms and bound in the (Ig) molecules forms as light chains that are evident in the serum and in urine. The purpose of this study was to evaluate the FLCs and TLCs approaches in screening serum and urine samples of patients with MM, doing so in comparison to the results of immunofixation (IFE) assessment. A second purpose was to assess the suitability of the collected material for obtaining the most reliable results. The results of serum FLCs (sFLCs) assays suggest that this approach is of the highest reliability and diagnostic usefulness in the detection of MG with excess production of FLCs, in comparison to other available tests. In our work, when κ band light chains were detected in serum IFE (sIFE), 91% patients had their FLCs concentrations beyond the reference range, whereas 89% patients had increased λ FLCs when λ band light chains were detected in sIFE. We also found abnormal sFLC κ/λ ratios in 86.4% and 88.9% of all subject patients who had κ or λ band light chains detected in their sIFE, respectively.

Free light chains of immunoglobulins in the cerebrospinal fluid of human immunodeficiency virus type 1-infected patients

The presence of immunoglobulin (Ig) free light chains (FLC) was investigated in the cerebrospinal fluid (CSF) of human immunodeficiency virus type 1 (HIV-1)-infected patients. Intrathecal synthesis of FLC was demonstrated in 80% of the patients, even in the absence of oligoclonal Ig. The FLC patterns were characterized by restricted heterogeneity with regard to both isoelectric point and the molecular weight, and were mainly composed by dimers rather than monomers. A striking prevalence of lambda FLC was also observed. Local production of FLC can be taken as a marker of an ongoing immunopathological process within the central nervous system (CNS) in HIV-1-infected patients. A deregulation of Ig production by intrathecally activated B cells may be hypothesized.

Free kappa and lambda light chain levels in the cerebrospinal fluid of patients with multiple sclerosis and other neurological diseases

Free kappa and lambda light chains were assayed by particle-counting immunoassay in cerebrospinal fluid (CSF) from patients with various neurological disorders. Detection limits were 25 and 50 ng/ml, respectively. Values of free kappa chain were higher than 50 ng/ml (upper reference limit) in 155 of 191 (81%) multiple sclerosis (MS) patients, in 100 of 168 (60%) patients with central nervous system (CNS) infections but in 41 of 217 (19%) patients with other neurological disorders. Free kappa chains were also assayed in 273 matched sera. The mean concentration in the control group (1.58 μg/ml; SD: 0.41) did not differ significantly from those in MS sera (1.63 μg/ml; SD: 0.43). The free kappa chain index was increased in 86% of MS patients and in 40% of patients with CNS infections. Regarding free lambda chains, CSF values were higher than 240 ng/ml (upper reference limit) in most neurological disorders (50–100%). However, the use of a lambda chain index increased the specificity of the assay as this index was higher than the upper reference value in 86% of MS patients and in only 23% of patients with infectious diseases. In MS, high levels of free kappa and lambda indices correlated significantly ( P < 0.01) with either the presence of oligoclonal bands or a high IgG index. Local synthesis of free light chains is an additional marker of an ongoing immune response within the CNS, especially in MS.

Induction of balanced immunoglobulin chain synthesis in free light chain-producing lymphocytes by mitogen stimulation.

Neoplastic cells from 2 cases of CLL synthesized and secreted excess free Ig light chain in culture, confirmed by precipitation with anti-idiotypic antibody. Small and medium sized normal human spleen cell subpopulations, staining predominantly for surface IgM and D, also synthesized and secreted excess free light chain. PWM stimulation induced balanced synthesis of heavy and light chains in CLL and normal spleen subpopulations after 6 days in culture, accompanied in spleen but not CLL by the appearance of mature plasma cells. These data demonstrate that normal cell counterparts of neoplastic lymphoid synthesis patterns can be identified in spleen. Furthermore, the synthesis pattern alteration after PWM stimulation suggests a relationship between free light chain synthesis and B cell immaturity. The failure of CLL cells to develop into detectable plasma cells suggests a restricted maturation response to mitogen compared with normal spleen.

Immunoglobulin synthesis by neoplastic B lymphocytes: free light chain synthesis as a marker of B cell differentiation.

Immunoglobulin synthesis has been investigated in 55 cases of B lymphocytic disease. Free light chain was the predominant product of Ig synthesis and the sole secreted Ig product from neoplasms lacking surface Ig or expressing sparse surface IgM as detected by fluorescent-labeled antibody. In contrast, neoplastic cells expressing strong surface IgM or IgG synthesized and secreted balanced amounts of heavy and light chain. Intermediate patterns of synthesis were shown by neoplastic cells expressing IgM with IgD. These patterns of synthesis occurred irrespective of the disease entity and are discussed in relation to models of B cell maturation.