The Association of Serum Free Light Chains With Mortality and Progression to End-Stage Renal Disease in Chronic Kidney Disease: Systematic Review and Individual Patient Data Meta-analysis.

OBJECTIVE: To clarify the associations between polyclonal serum free light chain (sFLC) levels and adverse outcomes in patients with chronic kidney disease (CKD) by conducting a systematic review and individual patient data meta-analyses. PATIENTS AND METHODS: On December 28, 2016, we searched 4 databases (MEDLINE, Embase, CINAHL, and PubMed) and conference proceedings for studies presenting independent analyses of associations between sFLC levels and mortality or progression to end-stage renal disease (ESRD) in patients with CKD. Study quality was assessed in 5 domains: sample selection, measurement, attrition, reporting, and funding. RESULTS: Five prospective cohort studies were included, judged moderate to good quality, involving 3912 participants in total. In multivariable meta-analyses, sFLC (kappa+lambda) levels were independently associated with mortality (5 studies, 3680 participants; hazard ratio [HR], 1.04 [95% CI, 1.03-1.06] per 10 mg/L increase in sFLC levels) and progression to ESRD (3 studies, 1848 participants; HR, 1.01 [95% CI, 1.00-1.03] per 10 mg/L increase in sFLC levels). The sFLC values above the upper limit of normal (43.3 mg/L) were independently associated with mortality (HR, 1.45 [95% CI, 1.14-1.85]) and ESRD (HR, 3.25 [95% CI, 1.32-7.99]). CONCLUSION: Higher levels of sFLCs are independently associated with higher risk of mortality and ESRD in patients with CKD. Future work is needed to explore the biological role of sFLCs in adverse outcomes in CKD, and their use in risk stratification.

Prolonged in vivo tumour retention of a human diabody targeting the extracellular domain of human HER2/neu.

Single-chain Fv (scFv) molecules exhibit highly specific tumour-targeting properties in tumour-bearing mice. However, because of their smaller size and monovalent binding, the quantities of radiolabelled scFv retained in tumours limit their therapeutic applications. Diabodies are dimeric antibody-based molecules composed of two non-covalently associated scFv that bind to antigen in a divalent manner. In vitro, diabodies produced from the anti-HER2/neu (c-erbB-2) scFv C6.5 displayed approximately 40-fold greater affinity for HER2/neu by surface plasmon resonance biosensor measurements and significantly prolonged association with antigen on the surface of SK-OV-3 cells (t1/2 cell surface retention of > 5 h vs 5 min) compared with C6.5 scFv. In SK-OV-3 tumour-bearing scid mice, radioiodinated C6.5 diabody displayed a highly favourable balance of quantitative tumour retention and specificity. By as early as 4 h after i.v. administration, significantly more diabody was retained in tumour (10 %ID g(-1)) than in blood (6.7 %ID ml(-1)) or normal tissue (liver, 2.8 %ID g(-1); lung, 7.1 %ID g(-1); kidney, 5.2 %ID g(-1)). Over the next 20 h, the quantity present in blood and most tissues dropped approximately tenfold, while the tumour retained 6.5 %ID g(-1) or about two-thirds of its 4-h value. In contrast, the 24-h tumour retention of radioiodinated C6.5 scFv monomer was only 1 %ID g(-1). When diabody retentions were examined over the course of a 72-h study and cumulative area under the curve (AUC) values were determined, the resulting tumor-organ AUC ratios were found to be superior to those previously reported for other monovalent or divalent scFv molecules. In conclusion, the diabody format provides the C6.5 molecule with a distinct in vitro and in vivo targeting advantage and has promise as a delivery vehicle for therapeutic agents.

Administration of disulfide-stabilized Fv-immunotoxins B1(dsFv)-PE38 and B3(dsFv)-PE38 by continuous infusion increases their efficacy in curing large tumor xenografts in nude mice.

B1 (dsFv)-PE38 and B3(dsFv)-PE38 are recombinant immunotoxins in which the Fv fragments of MAbs B1 and B3, respectively, are stabilized by an engineered interchain disulfide bond and are fused at their C-termini to a modified Pseudomonas exotoxin from which the cell-binding domain has been deleted (PE38). Both immunotoxins have been shown to be specifically cytotoxic toward human cancer cell lines which express Le gamma-related carbohydrates on their surface, and when given i.v., eradicated 30- to 50-mm3 s.c. A431 tumors growing in nude mice. A major advantage of dsFv-immunotoxins is their stability at 37 degrees C compared with the relatively unstable single-chain Fvs. This allows them to be given continuously by osmotic pumps placed in the peritoneal cavity. In an attempt to increase the therapeutic index of the immunotoxins, we have now delivered them continuously for 6 days through mini-osmotic pumps placed in the peritoneal cavity of tumor-bearing nude mice. Using this mode of administration, we were able to maintain a constant level of immunotoxin in the serum which was non-toxic to the mice, but caused complete regressions of large 150- to 200-mm3 tumors which lasted for over a month at 1/11 of the LD50 with B1(dsFv)-PE38 and 1/6 of the LD50 with B3(dsFv)-PE38. Complete regression of tumors of similar size could also be achieved by i.v. bolus injections of these immunotoxins at 1/7 of the LD50 with B1(dsFv)-PE38) and 1/3 of the LD50 with B3(dsFv)-PE38. These results suggest that in patients it may be advantageous to administer dsFv-immunotoxins by continuous infusion, since a larger therapeutic index is achieved.

An immunoglobulin light chain from a lupus-prone mouse induces autoantibodies in normal mice.

Autoantibodies against the 70-kD U1 RNP nucleoprotein autoantigen and DNA were elicited in normal BALB/c mice with a purified Ig light chain. This light chain, derived from a lupus-prone MRL-lpr/lpr mouse, has two distinctive properties: it contains an idiotypic marker recognized by a monoclonal MRL-lpr/lpr anti-snRNP autoantibody, and the amino acid sequence of its third hypervariable region (CDR3) is homologous to a sequence in an antigenic region of the 70-kD U1 RNP polypeptide. The results demonstrate that an Ig idiotype that mimics an autoantigen can induce autoimmunization.

Experimental nephropathy induced by human polyclonal light chains.

We describe the nephrotoxic effects of a preparation of light chains (LC) obtained by reduction and alkylation of human IgG. The acute renal lesions in rats are dependent upon the dose and route of LC administration. The kidney alterations were not observed in animals treated with comparable amounts of human albumin or the F(ab')2 fragment of human IgG. Intravenous bolus injection of 120 mg LC into 80-100 g hydropenic rats induced extensive cast formation in distal and collecting renal tubules, which were similar to the human "myeloma kidney". In contrast, the slow infusion of the same amount of LC over 1 h produced degenerative changes in the proximal tubular cells without extensive cast formation. The morphological alterations of the kidney were investigated by classical histological methods, by immunofluorescence and in thin sections stained with toluidine blue. Urinary excretion and kidney content of the lysosomal enzyme N-acetyl-beta-D-glucosaminidase were increased only in the group of animals infused with LC. These findings may be relevant to the pathogenesis of human nephropathy occurring in multiple myeloma and in some autoimmune diseases.