IgGs containing light chains of the λ- and κ- type and of all subclasses (IgG1–IgG4) from the sera of patients with systemic lupus erythematosus hydrolyze myelin basic protein

Abstract

Human myelin basic protein (hMBP)-hydrolyzing activity was recently shown to be an intrinsic property of antibodies from systemic lupus erythematosus (SLE) patients. Here, we present the first evidence demonstrating a significant diversity of different fractions of polyclonal IgGs (pIgGs) from SLE patients in their affinity for hMBP and in the ability of pIgGs to hydrolyze hMBP at different optimal pH values (5.3-9.5); the pH profiles of IgG1, IgG2, IgG3 and IgG4 were unique. IgGs containing the λ-type of light chains demonstrated higher relative activities (RAs) in the hydrolysis of hMBP and its oligopeptides (OPs) than κ-IgGs. IgGs of all four subclasses were catalytically active; their RAs in the hydrolysis of hMBP increased in the following order: IgG4 < IgG2 < IgG3 < IgG1. Metal-dependent proteolytic activity of λ-IgG, IgG1, IgG2 and IgG3 was higher than their serine protease-like activity, while these activities of κ-IgG were comparable. Phenylmethylsulfonylfluoride had almost no effect on the activity of IgG4, while EDTA significantly suppressed its activity. The RAs of λ-IgG in the hydrolysis of four OPs corresponding to different cleavage sites of hMBP were remarkably higher than those for κ-IgGs. IgG1-IgG4 demonstrated different RAs and patterns of hydrolysis of these four OPs. Although combination of Ca²⁺ plus Mg²⁺ was the best in the activation of IgG1 and IgG2, IgG3 and IgG4 demonstrated the highest activity in the presence of Ca²⁺ plus Co²⁺. The ratio of the RAs of λ-IgG, κ-IgG and IgG1-IgG4 preparations in all analyzed cases was individual for each preparation.

Catalytic Antibodies in Norm and Systemic Lupus Erythematosus

“…The relative contribution of SLE IgGs of different subclasses to the total proteolytic activity of IgGmix was estimated in a similar way: IgG1 (73.0 ± 3.4%) > IgG2 (19.1 ± 1.8%) > IgG3 (6.7 ± 0.3%) > IgG4 (1.2 ± 0.2%). These data provided the first evidence that SLE IgGs of all types possess MBP-hydrolyzing activity, but they differ in the relative contribution into the total activity of proteolytic activity of polyclonal abzymes [76]. Kappa-IgGs and lambda-IgGs hydrolyzed MBP within a wide range of pH values (5.3-9.5) and showed comparable pH dependencies, while the pH profiles for IgG1-IgG4 were unique (Figure 17).…”

“…In addition, the level of lymphocyte proliferation as well as cell apoptosis in different organs including bone marrow of healthy MRL-lpr/lpr and EAE mice, at stages of their prediseases and deep pathologies were also comparable [32]. In addition, it was shown that abzymes hydrolyzing MBP are formed in the early stages of human MS, unlike in later stages of SLE, while the reverse situation was observed for abzymes with DNase activity [70][71][72][73][74][75][76][77][78][79][80][81][82][83][84][85][86][87]. One gets the impression that SLE and MS differ greatly in their initial stages but become to some extent more similar at the later stages of these diseases.…”

“…[13,19]). We applied a set of these strict criteria [9,[13][14][15][16][17][18][19][20][21][22] for the analysis of DNase and RNase [11,31,64,65,[70][71][72][73][74][75], MBPhydrolyzing [76][77][78][79], ATPase [30], and amylase [29,[88][89][90][91] activities as intrinsic properties of IgG and/or IgM and IgA antibodies from sera of SLE patients and mice. Several more important of them may be summarized as follows: (1) all Abs were electrophoretically homogeneous; (2) FPLC gel filtration of these Abs under conditions destroying strong noncovalent complexes (acidic buffer, pH 2.6) did not abolish these activities, and activities peaks exactly coincided with peaks of intact Abs; (3) immobilized mouse IgGs against the light chains of human Abs absorbed completely these activities; these activity's peaks coincided with the peaks of Abs eluted using acidic buffer; and (4) F(ab) and F(ab)2 fragments of Abs showed to some extent comparable levels of the activities comparing with intact Abzs.…”

“…Application of the strict criteria to show that MBP-hydrolyzing activity is intrinsic property of IgGs from sera of SLE patients [76,77]. Affinity chromatography of the IgGmix (Abs of 10 patients) using Sepharose bearing mouse Abs against human IgGs (A) and FPLC gel filtration IgGmix on column with Superdex 200 in acidic buffer (pH 2.6) after incubation of Abs in the same buffer (B): (-), absorbance at 280 nm (A280); (□), relative activity (RA) of IgGmix in the hydrolysis of human MBP (A and B).…”

“…In addition, the mixture of electrophoretically homogeneous IgGmix was separated to fractions of IgG1-IgG4 subclasses and to fractions of IgGs containing lambda-and kappa-type of light [76]. The immunological purity of IgGs of all types was revealed by ELISA; the preparations of IgG1, IgG2, IgG3, and IgG4 did not contain IgGs of other subclasses.…”