Copper(II)-induced Ig-G aggregates become irreversibly aggregated by hydrogen peroxide.

SAPORITO MAGRIÑA C; LOPEZ MONTAÑANA, L; FACIO, ML; LAIRION F; REPETTO, MG

Congreso; Reunión conjunta SAIC. SAI & FAIC, SAFIS 2022. LXVII Reunión Anual de la Sociedad Argentina de Investigación Clínica (SAIC), lXX Reunión Anual de la Sociedad Argentina de Inmunología (SAI) & 3er Congreso Franco-Argentino de Inmunología (FAIC), Reunión Anu; 2022

Sociedad Argentina de investigacion Clinica

Proteins are prone to aggregation and free cupric ions (Cu(II)) promote this process. Such aggregates are found in plasma as detergent resistant aggregates (DRA). Cu(II) ions are found in the micromolar range in plasma but rise in pathologies such as Wilson Disease. We have shown that IgGs are selectively aggregated by Cu(II). Therefore, plasma Cu(II) may be a driving force for IgG aggregation. Additionally, DRA have been reported to increase in elders. We speculate that the oxidative modifications of the aggregates impair their clearance and drive their accumulation over the years. Methods: Optic density (OD), Lowry assay, Carbonyl content (CO), SDS-PAGE. Results: Followed by OD, Cu(II) and Zn(II) induce IgG aggregation at 5 µM and 20 µM, respectively (n=3). Zn(II) was employed as a non-redox active metal. Upon addition of H2O2, Cu(II)-induced aggregates (Cu(II)IA) become irreversibly insoluble while Zn(II)-induced aggregates (Zn(II)IA) are fully dissolved upon metal removal by EDTA. Cu(II)IA in the presence of H2O2 are also SDS-resistant whereas Zn(II)IA are completely soluble (n=3). Cu(II)IA become irreversibly insoluble in the presence of H2O2 (4 mM). However, when followed by SDS-PAGE, concentrations of 50 µM H2O2 yet yield Cu(II)IA with higher mass than monomeric IgG, indicating the formation of soluble DRA (n=3). In contrast, when Zn(II)IA with H2O2 mixtures are assessed by SDS-PAGE, no soluble higher mass aggregates are observed. Furthermore, the CO content significantly rises when IgGs are incubated with H2O2 in the presence of Cu(II) when compared to H2O2 alone (p