Journal Article

Mercury exposure in protein A immunoadsorption

Ludwig Kramer, Edith Bauer, Martin Jansen, Daniela Reiter, Kurt Derfler and Andreas Schaffer

in Nephrology Dialysis Transplantation

Published on behalf of European Renal Association - European Dialysis and Transplant Assoc

Volume 19, issue 2, pages 451-456
Published in print February 2004 | ISSN: 0931-0509
Published online February 2004 | e-ISSN: 1460-2385 | DOI: http://dx.doi.org/10.1093/ndt/gfg554
Mercury exposure in protein A immunoadsorption

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Background. Immunoadsorption is increasingly used to treat antibody-mediated autoimmune diseases. To prevent microbial growth during storage, reusable protein A–Sepharose gel columns are primed with ethyl mercury thiosalicylate (thiomersal, 0.1% solution) and rinsed with phosphate buffer before use. In this study, we tested the hypothesis of systemic mercury exposure in protein A immunoadsorption.

Methods. Whole blood mercury levels were measured by atomic absorption spectroscopy before and after protein A immunoadsorption (11 patients, 26 treatments), anti-IgG immunoadsorption (eight patients, 13 treatments) and LDL apheresis (DALI and Therasorb systems; nine patients, 14 treatments).

Results. Patients treated with protein A immunoadsorption had significantly elevated baseline mercury levels compared with the other groups, which were not different from healthy controls. Following protein A immunoadsorption, mercury levels increased from 5.9±1.4 μg/l (mean±SEM, normal, <5 μg/l) to 32.3±5.7 μg/l, P<0.001). In one intensively treated patient, acute neurological toxicity developed at a mercury level of 107 μg/l. Symptoms abated slowly and did not recur after switching to a thiomersal-free system and chelation therapy. No mercury release to patients occurred in anti-IgG immunoadsorption or LDL apheresis treatments.

Conclusion. This preliminary report suggests that protein A immunoadsorption columns primed with thiomersal during storage may cause a sustained increase of systemic mercury concentrations, which exceed current safety recommendations in a proportion of patients. Considering the potential for mercury-induced toxicity, every effort should be undertaken to reduce systemic mercury exposure, either by adding chelators to the rinsing solution or ideally by replacement of thiomersal.

Keywords: immunoadsorption; mercury; thiomersal; toxicity; tremor

Journal Article.  3112 words.  Illustrated.

Subjects: Nephrology

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