Peculiarities of abzymes from sera and milk of healthy donors and patients with autoimmune and viral diseases

Catalase activity of IgG antibodies from the sera of healthy donors and patients with schizophrenia

We present first evidence showing that some electrophoretically homogeneous IgGs from the sera of patients with schizophrenia (36.4%) and their Fab and F(ab)2 fragments as well as from healthy donors (33.3%) possess catalase activity. The relative catalase activity of IgGs from the sera of individual schizophrenia patients (and healthy donors) significantly varied from patient to patient, but the activity of IgGs from healthy donors is on average 15.8-fold lower than that for schizophrenia patients. After extensive dialysis of purified IgGs against EDTA chelating metal ions, the relative catalase activity of IgGs decreases on average approximately 2.5-3.7-fold; all IgGs possess metal-dependent and independent catalase activity. The addition of external Me2+ ions to dialyzed and non-dialyzed IgGs leads to a significant increase in their activity. The best activator of dialyzed and non-dialyzed IgGs is Co2+, the activation by Cu2+, Mn2+, and Ni2+ ions were rare and always lower than by Co2+. Every IgG preparation demonstrates several individual sets of very well expressed pH optima in the pH range from 4.0 to 9.5. These data speak for the individual repertoire of catalase IgGs in every person and an extreme diversity of abzymes in their pH optima and activation by different metal ions. It is known that antioxidant enzymes such as superoxide dismutases, catalases, and glutathione peroxidases represent critical defense mechanisms preventing oxidative modifications of DNA, proteins, and lipids. Catalase activity of human IgGs could probably also play a major role in the protection of organisms from oxidative stress and toxic compounds.

DNA-damaging autoantibodies and cancer: the lupus butterfly theory

Autoantibodies reactive against host DNA are detectable in the circulation of most people with systemic lupus erythematosus (SLE). The long-held view that antibodies cannot penetrate live cells has been disproved. A subset of lupus autoantibodies penetrate cells, translocate to nuclei, and inhibit DNA repair or directly damages DNA. The result of these effects depends on the microenvironment and genetic traits of the cell. Some DNA-damaging antibodies alone have little impact on normal cells, but in the presence of other conditions, such as pre-existing DNA-repair defects, can become highly toxic. These findings raise new questions about autoimmunity and DNA damage, and reveal opportunities for new targeted therapies against malignancies particularly vulnerable to DNA damage. In this Perspectives article, we review the known associations between SLE, DNA damage and cancer, and propose a theory for the effects of DNA-damaging autoantibodies on SLE pathophysiology and cancer risk.

IgG abzymes with peroxidase and oxidoreductase activities from the sera of healthy humans

We present the evidence showing that small fractions of electrophoretically homogeneous immunoglobulin G (IgGs) from the sera of healthy humans and their Fab and F(ab)2 fragments oxidize 3,3'-diaminobenzidine through a peroxidase activity in the presence of H2 O2 and through an oxidoreductase activity in the absence of H2 O2 . During purification on protein G-Sepharose and gel filtration, the polyclonal IgGs partially lose the Me(2+) ions. After extensive dialysis of purified Abs against agents chelating metal ions, the relative peroxidase activity decreased dependently of IgG analyzed from 100 to ~10-85%, while oxidoreductase activity from 100 to 14-83%. Addition of external metal ions to dialyzed and non-dialyzed IgGs leads to a significant increase in their activity. Chromatography of the IgGs on Chelex non-charged with Cu(2+) ions results in the adsorption of a small IgG fraction bound with metal ions (~5%), while Chelex charged with Cu(2+) ions bind additionally ~38% of the total IgGs. Separation of Abs on both sorbents results in IgG separation to many different subfractions demonstrating various affinities to the chelating resin and different levels of the specific oxidoreductase and peroxidase activities. In the presence of external Cu(2+) ions, the specific peroxidase activity of several IgG subfractions achieves 20-27 % as compared with horseradish peroxidase (HRP, taken for 100%). The oxidoreductase activity of these fractions is ~4-6-fold higher than that for HRP. Antioxidant enzymes such as superoxide dismutases, catalases, and glutathione peroxidases are known to represent critical defence mechanisms for preventing oxidative modifications of DNA, proteins, and lipids. Peroxidase and oxidoreductase activities of human IgGs could also play an important role in the protection of organisms from oxidative stress and toxic compounds.

DNase, RNase, and phosphatase activities of antibodies formed upon immunization by DNA, DNase I, and DNase II

Relative DNase, RNase (efficiency of hydrolysis of ribo- and deoxyribooligonucleotides (ON)), and phosphatase (removal of the ON 5' terminal phosphate) catalytic activities of antibodies (AB) obtained after rabbit immunization by DNA, DNase I, and DNase II were compared. It is shown that electrophoretically homogeneous preparations of polyclonal AB from non-immunized rabbits did not exhibit such activities. Immunization of rabbits by DNA, DNase I, and DNase II results in generation of IgG abzymes that exhibit high activity in the ON hydrolysis reaction and even higher activity in cleavage of 5' terminal phosphate of ON. In this case K(m) values for supercoiled plasmid DNA and ON found in reactions of their AB-dependent nuclease hydrolysis and phosphatase cleavage of 5' terminal phosphate differ by 2-4 orders of magnitude. This shows that nuclease and phosphatase activities belong to different abzyme fractions within polyclonal AB. Thus, in this work data indicative of the possibility of a formation of antibodies exhibiting phosphatase activity after immunization of animals with DNA, DNase I, and DNase II, were obtained for the first time. Possible reasons for production of AB with phosphatase activity after immunization of rabbits with these immunogens are discussed.