Leading Edge 2020 Issue 1

www.alphalabs.co.uk 9 Printed on Recycled Paper In addition, each laboratory was given a further two anonymised control sera from healthy donors. The laboratories tested each sample for anti-GM1, anti-GM2, anti-GD1a, anti-GD1b, anti-GD3, anti-GQ1b, anti-GT1a, anti-GT1b; all antigens were tested for IgG and IgM reactivities. Of the 15 laboratories involved, one of these was using the BÜHLMANN GanglioCombi Light ELISA, a further six laboratories were using in-house ELISAs, and the remaining eight laboratories were using line/dot-blot methods from various manufacturers. The results obtained for sample 1 across the 15 laboratories are shown in Table 2. Laboratory Assay GM1 GM2 GD1a GD1b GQ1b GT1a 1 ELISA - BÜHLMANN GanglioCombi Light Positive 2 ELISA (in-house) False Negative False Positive False Positive 3 ELISA (in-house) False Negative 4 ELISA (in-house) False Negative False Positive 5 ELISA (in-house) False Negative 6 ELISA (in-house) False Negative 7 ELISA (in-house) False Negative 8 Line/dot-blot (Dotzen/Zentec) False Negative 9 Line/dot-blot (Dotzen/Zentec) False Negative 10 Line/dot-blot (Dotzen/Zentec) False Negative 11 Line/dot-blot (Euroimmun) False Negative 12 Line/dot-blot (Euroimmun) False Negative 13 Line/dot-blot (Euroimmun) False Negative 14 Line/dot-blot (generic assays) False Negative 15 Line/dot-blot (generic assays) False Negative False Positive Table 2 : Comparison of anti-ganglioside patient test result across different laboratories and assays Expected anti-ganglioside antibodies: GM1 IgG Sample Expected Autoantibody Profile Labs performing line/dotblot Labs performing in-house/ commercial ELISAs BÜHLMANN GanglioCombi ELISA 2 anti-GM1 IgG 3/7 3/7 13/13 3 anti-GD1b IgM & anti-GQ1b IgM 7/7 5/7 13/13 4 anti-GQ1b IgM 5/7 4/7 13/13 Table 3 : Which methods obtained the correct autoantibody profiles? Based on the clinical phenotype of the patient providing sample 1, you would expect a positive result for the anti-GM1 antibody only. The collated results show that the GanglioCombi Light ELISA, manufactured by BÜHLMANN, was the only testing method to produce the expected result. All the other test methods had a false negative result for anti-GM1, and there were a few false positive results for some of the other methods. In addition to this, 13 of these laboratories were given the opportunity to test the same samples with the BÜHLMANN GanglioCombi MAG ELISA. The purpose of this was to evaluate the inter-laboratory variability for the assay. The results showed 100% concordance between the 13 laboratories for sample 2 (anti-GM1 IgG positive), sample 3 (anti-GD1b IgM positive), sample 4 (anti-GD1b IgM & anti-GQ1b IgM positive), and sample 5 (all negative). Further to the excellent inter-laboratory variability demonstrated, the GanglioCombi MAG ELISA performed well when evaluated against the clinical phenotype of the patients providing the samples. Table 3 shows the expected autoantibody profile for samples 2, 3 and 4, and how many laboratories, using each method, managed to obtain the correct result. All 13 laboratories using the GanglioCombi MAG ELISA obtained the correct results for samples 2, 3 and 4; the GanglioCombi MAG ELISA outperformed the other methods being used (line/dot-blot and in-house ELISAs), as not all laboratories using these methods obtained the expected result. Reference View the full EQAS report: Franciotta et al. Anti-ganglioside antibodies: experience from the Italian Association of Neuroimmunology external quality assessment scheme. Clin Chem Lab Med 2018; 56(11): 1921–1925. https://doi.org/10.1515/cclm-2018-0234 For more information on the BÜHLMANN neuroimmunology kits please visit www.alphalabs.co.uk/neuroimmunology