IgG Subclass Autoimmunity Analysis In Sera Of Patients With Pseudoexfoliation Syndrome, Pseudoexfoliation Glaucoma and Cataract Controls

Abstract

Purpose: : Using protein microarrays we could previously show evidence for differentiation between pseudoexfoliation syndrom (PEXS) and pseudoexfoliation glaucoma (PEXG) on the basis of autoantibody profiles. To gain further insight into immunoreactivities of PEXS and PEXG patients we analyzed the IgG_1-4 antibody reactivities in these patients and cataract controls (CAT).

Methods: : Sera of patients with PEXG (n=17), PEXS (n=17) and controls with cataract (n=17) were used for antibody analysis . Analyses were performed using protein-microarrays, which were prepared by spotting 51 different ocular antigens onto microarray slides. Arrays were incubated with sera (1:250), and were treated with anti-IgG_1-4 antibodies. For visualization of the antibody-antigen-reactions we used a fluorescence labeled tertiary antibody. Emitted signals were digitized and spot intensities were compared using diverse statistical techniques, such as ANOVA and multivariate discriminant analysis.

Results: : The intensities of the antibody-antigen-reactions response decreased from IgG₁ to IgG₄. The general immunoreactivity distribution did not differ between IgG subclasses (IgG₁ 40%, IgG₂ 24%, IgG₃ 21%, IgG₄ 15%). However, the immunoreactivity distribution of some antigens differed significantly e.g. Macroglobulin (CAT IgG₁ 46%, IgG₂ 9%, IgG₃ 32%, IgG₄ 13%, PEXG IgG₁ 48%, IgG₂ 10%, IgG₃ 22%, IgG₄ 20%, PEXS IgG₁ 58%, IgG₂ 9%, IgG₃ 18%, IgG₄ 15%). The normalized immunoreactivities showed also significant differences for 7 antigens for IgG₁ e.g. Neuro specific enolase (CAT vs PEXS p≤0.01 and PEXG vs PEXS p≤0.01), for 6 antigens for IgG₂ e.g. γ-Synuclein (PEXG vs PEXS p≤0.01), α-1-Antitrypsin (CAT vs PEXS p≤0.03), for 17 antigens for IgG₃ e.g. Neuro specific enolase (CAT vs PEXS p≤0.01 and PEXG vs PEXS p≤0.02) and for 8 antigens for IgG₄ e.g. Macroglobulin (CAT vs PEXS p≤0.04 and PEXG vs PEXS p≤0.02).

Conclusions: : The general immunoreactivity distribution of the IgG subclasses did not distinguish between PEXS, PEXG and CAT. However,we found statisticially significant differences for all IgG subclasses between study groups. The most significant differences in the immunoreactivity could be shown for IgG_3, which is the strongest activator of the complement cascade. This fact seems to support the theory of the involvement of autoimmunity in glaucoma pathogenesis.

Keywords: immunomodulation/immunoregulation • autoimmune disease • detection