Objective: A task force of scientists at the International Congress on Antiphospholipid Antibodies recognized that phosphatidylserine-dependent antiprothrombin antibodies (aPS/ PT) might contribute to a better identification of antiphospholipid syndrome (APS). Accordingly, initial and replication retrospective, cross-sectional multicentre studies were conducted to ascertain the value of aPS/PT for APS diagnosis. Methods: In the initial study (eight centres, seven countries), clinical/laboratory data were retrospectively collected. Serum/plasma samples were tested for IgG aPS/PT at Inova Diagnostics (Inova) using two ELISA kits. A replication study (five centres, five countries) was carried out afterwards. Results: In the initial study (n ¼ 247), a moderate agreement between the IgG aPS/PT Inova and MBL ELISA kits was observed (k ¼ 0.598). IgG aPS/PT were more prevalent in APS patients (51%) than in those without (9%), OR 10.8, 95% CI (4.0-29.3), p < 0.0001. Sensitivity, specificity, positive (LRþ) and negative (LR-) likelihood ratio of IgG aPS/PT for APS diagnosis were 51%, 91%, 5.9 and 0.5, respectively. In the replication study (n ¼ 214), a moderate/substantial agreement between the IgG aPS/PT results obtained with both ELISA kits was observed (k ¼ 0.630). IgG aPS/PT were more prevalent in APS patients (47%) than in those without (12%), OR 6.4, 95% CI (2.6-16), p < 0.0001. Sensitivity, specificity, LR þ and LR-for APS diagnosis were 47%, 88%, 3.9 and 0.6, respectively. Conclusions: IgG aPS/PT detection is an easily performed laboratory parameter that might contribute to a better and more complete identification of patients with APS. Lupus (2016) 0, 1-11.
Renal failure is a frequent complication in patients with multiple myeloma. Immunoglobulin free light chains (FLCs) form casts in the distal tubules, resulting in renal obstruction, and are also directly toxic to proximal renal tubules. Removal of FLCs contributes to renal recovery. High cut-off (HCO) membrane Theralite2100, protein leaking dialyzer PES210Dα, plasma separator Evacure1A20 and β(2) microglobulin adsorption column LixelleS-35 were compared in their FLC removal rate. Dialysis using Theralite2100 or Evacure1A20, diafiltration using PES210Dα and adsorption using LixelleS-35 were performed in an in vitro circuit. The highest removal rate was obtained by Theralite2100 dialysis among the four blood purification methods. Albumin loss was also the greatest in Theralite2100 dialysis. The removal content of FLCs per 1 g albumin loss was better in PES210Dα diafiltration. The removal rate of FLCs by Evacure EC1A-20 dialysis was the third highest. Adsorption of FLCs by the β(2) microglobulin adsorption column Lixelle S-35 was confirmed. In conclusion, Theralite2100 dialysis was the best in removal of FLCs. PES210Dα diafiltration can remove FLCs with smaller loss of albumin.
Background. Free immunoglobulin light chains (FLCs) accumulate at high levels in the blood of dialysis patients and are likely to cause immunodeficiency during periods of dialysis. Our group examined the blood FLC concentration, κ/λ ratio and rates of FLC removal in different dialysis modes using different dialysis membranes.Methods. Polymethylmethacrylate (PMMA) membrane (BG-PQ, Toray) under the haemodialysis (HD) condition was used for seven chronic maintenance dialysis patients who had been treated by hemodiafiltration (HDF) (five polyester-polymer alloy (PEPA) and two polysulphone) in a crossover fashion. FLCs in serum were measured with a FREELITE™ Human Kappa Free Kit and Lambda Free Kit prepared by Binding Site, UK (supplied by Medical & Biological Laboratories Co., Ltd, Japan). Each κ-type and λ-type FLC was quantitatively measured with a Dade Behring BNII™. Western blotting was conducted using a goat anti-human κFLC polyclonal antibody.Results. The κ and λ serum FLCs in HD patients (n = 7) were 157.4 ± 88.9 and 121.9 ± 56.3 mg/L, respectively, and were accumulated in concentrations 4- to 16-fold higher than the concentrations in healthy controls. The κ/λ ratio was included in the reference range (0.26–1.65). In the HD cases dialysed with PMMA membrane, the FLCs were removed mainly by adsorption, leaving only very small quantities in the whole dialysis waste fluid. The ratio between the total removed quantity and albumin leakage ((κ+λ)/Alb) was higher in the PMMA HD group than in the HDF group, and the rate of κFLC removal was higher than the rate of λFLC removal. The serum κFLC in dialysis patients had a multimer structure. In western blotting, the adsorbed κFLC (including multimer structure) detected in the PMMA membrane exceeded that detected in the dialysate with the polysulphone membrane.Conclusions. Although the FLCs were removed at high rates under the HDF condition, they were also effectively removed by adsorption with the PMMA membrane under the HD condition. It may be possible to effectively remove the FLC multimer with a PMMA membrane via adsorption. In future studies on FLC removal in patients with chronic renal failure, it will be necessary to assess not only the quantity of simple removal from the blood but also the qualitative properties, such as the degree to which accumulation and removal rates depend on the κ/λ ratio and multimer structures.
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