Affinity and catalytic heterogeneity of polyclonal myelin basic protein‐hydrolyzing IgGs from sera of patients with multiple sclerosis

Abstract

Human myelin basic protein (hMBP)-hydrolyzing activity was recently shown to be an intrinsic property of antibodies (Abs) from multiple sclerosis (MS) patients. Here, we present the first evidence demonstrating a significant diversity of different fractions of polyclonal IgGs (pIgGs) from MS patients in their affinity for hMBP and in the ability of pIgGs to hydrolyze hBMP at different optimal pHs (3–10.5). IgGs containing λ- and κ-types of light chains demonstrated comparable relative activities in the hydrolysis of hMBP. IgGs of IgG1–IgG4 sub-classes were analyzed for catalytic activity. IgGs of all four sub-classes were catalytically active, with their contribution to the total activity of Abzs in the hydrolysis of hMBP and its 19-mer oligopeptide increasing in the order: IgG1 (1.5–2.1%) < IgG2 (4.9–12.8%) < IgG3 (14.7–25.0%) < IgG4 (71–78%). Our findings suggest that the immune systems of individual MS patients generate a variety of anti-hMBP abzymes with different catalytic properties, which can attack hMBP of myelin-proteolipid shell of axons, playing an important role in MS pathogenesis.

Multiple sites of the cleavage of 17- and 19-mer encephalytogenic oligopeptides corresponding to human myelin basic protein (MBP) by specific anti-MBP antibodies from patients with systemic lupus erythematosus

“…It was recently shown that incubation of many individual IgGs with iodoacetamide (a specific inhibitor of thiol proteases) or pepstatin A (a specific inhibitor of acidic proteases) has moderate effect (5-15%) on SLE Ab-dependent hydrolysis of MBP [9]; the same was demonstrated for MS IgGs, IgAs and IgMs [27][28][29][30][31]. However, PMSF, AEBSF (specific inhibitors of serine proteases), and EDTA (an inhibitor of metalloproteases) significantly suppressed the proteolytic activity of SLE and MS pIgGs in the case of MBP and OPs as substrates [9].…”

“…No activity was found for IgG fraction of healthy donors in the hydrolysis of MBP or different OPs (Fig. 1) [27][28][29][30][31]. The sites of MBP cleavage by MS IgGs determined by mass spectrometry were localized within four known immunodominant regions of MBP [31].…”

“…It was recently shown that, anti-MBP IgGs from the sera of patients with MS [27][28][29][30][31] and SLE [9] efficiently hydrolyze globular MBP but not many other tested proteins. No activity was found for IgG fraction of healthy donors in the hydrolysis of MBP or different OPs (Fig.…”

“…Electrophoretical and immunological homogeneity of the pIgGs was confirmed respectively by SDS-PAGE with silver staining and by Western blotting similarly to [9,[27][28][29][30]. To analyze an ''average'' situation, we have prepared a mixture of equal amounts of homogeneous pIgGs from the sera of ten SLE (sle-IgG mix ), ten MS (ms-IgG mix ) patients, and ten healthy donors (hd-IgG mix ).…”

“…It has been recently shown that MBP-hydrolyzing activity is an intrinsic property of IgGs, IgMs, and IgAs from the sera of MS patients [27][28][29][30] and the specific sites of the neural antigen cleaved by abzymes have been established [31]. Recognition and degradation of MBP peptides by serum auto-Abs was confirmed as a novel biomarker for MS [31].…”