AUTHOR=Nehring Josephine , Schirmbeck Lucia A. , Friebus-Kardash Justa , Dubler Denise , Huynh-Do Uyen , Chizzolini Carlo , Ribi Camillo , Trendelenburg Marten 

TITLE=Autoantibodies Against Albumin in Patients With Systemic Lupus Erythematosus

JOURNAL=Frontiers in Immunology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2018.02090

DOI=10.3389/fimmu.2018.02090

ISSN=1664-3224

ABSTRACT=<p><bold>Objectives:</bold> Autoantibodies and aberrant immune complexes are pathological hallmarks of systemic lupus erythematosus (SLE). This study aimed to determine the occurrence of IgG autoantibodies against human serum albumin (anti-HSA IgG) and their potential association with antibodies against bovine serum albumin (anti-BSA IgG) in patients with SLE.</p><p><bold>Methods:</bold> Sera of 180 SLE patients included to the Swiss SLE Cohort Study and 188 age- and sex-matched healthy controls were evaluated. Levels of anti-HSA IgG and anti-BSA IgG were quantified by ELISA. Selected samples were further characterized using serum fractions obtained by fast liquid chromatography (FPLC).</p><p><bold>Results:</bold> SLE patients had increased levels of anti-HSA IgG (<italic>p</italic> = 0.002) but similar levels of anti-BSA IgG compared to matched healthy controls. Anti-HSA IgG levels correlated with the SLE Disease Activity Index (SLEDAI), which was more pronounced in patients with an physician's global assessment (PGA) of ≥ 1 (<italic>r</italic> = 0.309, <italic>p</italic> = 0.0066). Anti-HSA IgG was partially complexed with serum albumin but also occurred as monomeric autoantibodies in highly positive SLE patients. A positive correlation between anti-HSA IgG and anti-BSA IgG was found that was stronger in SLE patients than in healthy controls (<italic>r</italic> = 0.3172, <italic>p</italic> &lt; 0.001 vs. <italic>r</italic> = 0.2122, <italic>p</italic> &lt; 0.0035). Binding of anti-BSA IgG was inhibited partially in the presence of HSA in samples with double positivity for anti-HSA and anti-BSA (median inhibition 47.9%, range 0.9–100%) and vice versa.</p><p><bold>Conclusion:</bold> In SLE patients there is an increased prevalence of anti-HSA IgG antibodies that are associated with SLE disease activity.</p>