DNA-hydrolyzing IgG antibodies from the blood of patients with acquired immune deficiency syndrome

DNase activity was analyzed in 110 IgG preparations from the blood of AIDS patients. The relative activity of the preparations varied markedly among patients, being reliably detectable in 96% of the preparations. It was shown with several rigid criteria that DNAase activity is an intrinsic property of antibodies (Abs) from AIDS patients. Not only intact IgG, but also isolated light chains of polyclonal Abs were shown to possess catalytic activity. The abzymes efficiently catalyzed DNA hydrolysis in a wide range of pH (5.0–9.5). The K _M and V _max values were evaluated for Ab-dependent hydrolysis of DNA.     

DNA-Hydrolyzing Antibodies from Sera of Autoimmune-Prone MRL/MpJ-lpr Mice

Catalytically active antibodies (abzymes) hydrolyzing proteins, polysaccharides, ATP, DNA, and RNA have been detected in the sera of patients with various autoimmune and some viral diseases, but abzymes from the sera of animals are practically unstudied. The development of lupus-like autoimmune disease of MRL/MpJ-lpr mice is an experimental model for study of autoimmune pathologies and immunopathogenesis. In this work, homogeneous IgG preparations were isolated from the sera of MRL/MpJ-lpr mice. These antibodies (Abs), their Fab-fragments, and isolated light chains were shown to possess catalytic activity in DNA hydrolysis, whereas Abs from the sera of control healthy mice did not hydrolyze DNA. The data demonstrate that DNA hydrolyzing activity is an intrinsic property of Abs from MRL/MpJ-lpr mice. It was shown that various markers of autoimmune pathologies (level of total protein concentration in urea (proteinuria), Abs titers to native and denatured DNA, and DNA-hydrolyzing activity of IgG) increased in animals with aging, but they noticeably increased (2-22 times) only after appearance of obvious indicators of pathology independently of age. The highest increase in proteinuria (25-fold), anti-DNA Abs titers (12-19-fold), and abzyme activity (120-fold) was found in mice after their immunization with DNA–protein complex.     

Antibodies against DNA hydrolyze DNA and RNA

In this work, rabbits were immunized with a high polymer DNA complexed with methylated BSA (mBSA) and by mBSA. It is shown that electrophoretically homogeneous preparations of polyclonal antibodies (Ab) from non-immunized rabbits and animals immunized by mBSA do not exhibit catalytic activity. Ab from the blood of rabbits immunized with the DNA-mBSA complex hydrolyzed poly(C) and different RNAs with efficiency exceeding that towards DNA by approximately 3–4 orders of magnitude. Affinity chromatography of the IgG on DNA cellulose separated the Ab into fractions hydrolyzing both RNA and DNA, and for the first time fractions that hydrolyze only RNA were found. Kinetic parameters that characterize the RNA and DNA hydrolysis by initial Ab preparations and their fractions obtained by separation on an affinity sorbent are compared.     

Comparison of DNA-Hydrolyzing Antibodies from the Cerebrospinal Fluid and Serum of Patients with Multiple Sclerosis

It was found that high-affinity anti-DNA antibodies were one of the major components of the intrathecal IgG response in multiple sclerosis (MS) patients [Williamson et al., PNAS, 2001]. Recently we have shown that IgGs from the sera of MS patients are active in the hydrolysis of DNA. Here we have shown, for the first time, that average concentration of total proteins (132-fold), total IgGs (194-fold) and anti-DNA antibodies (200-fold) in the sera is significantly higher than that in the cerebrospinal fluid (CSF) of fifteen MS patients. The relative activities of total protein from sera and CSFs varied remarkably from patient to patient. It was surprising that the specific DNase activity of the total protein of CSF reparations were 198-fold higher than the serum ones. Electrophoretically and immunologically homogeneous IgGs were obtained by sequential affinity chromatography of the CSF proteins on protein G-Sepharose and FPLC gel filtration. We present first evidence showing that IgGs from CSF not only bind but efficiently hydrolyze DNA and that average specific DNase activity of homogeneous antibodies from CSF is unpredictably ∼49-fold higher than that from the sera of the same MS patients. Some possible reasons of these findings are discussed. We suggest that DNase IgGs of CSF may promote important neuropathologic mechanisms in this chronic inflammatory disorder and MS pathogenesis development.     

IgG binding enhances DNAase I sensitivity of N-acetoxy-N-2-acetylaminofluorene-modified ΦX-174 RF DNA

DNA restriction fragments of фX-174 RF were modified with the carcinogen, N-acetoxy-N-2-acetylaminofluorene (N-Aco-AAF). Immune complexes of 5′-³²P-labeled AAF-modified DNA and rabbit immunoglobulin (IgG) against AAF-guanosine were specifically bound by surface membranes of Cowan I strain micrococci whose protein A binds the Fc portion of IgG. DNAase I sensitivity of the bound DNA was 20-fold greater than in solution, but the normal pattern of hydrolysis was not altered, as determined in sequencing gels. Nonadducted DNA ligated to AAF-modified DNA acquired the enhanced sensitivity to DNAase I hydrolysis when the ligation hybrid was immunobound.     

ELISA for bovine herpesvirus 1 (BHV1) antibody with HIRT supernatant

Detailed studies were made of the ability of HIRT supernatant (HS) from bovine herpesvirus 1 (BHV1) infected cultures to sensitize plates for enzyme-linked immunosorbent assay (ELISA). The ultracentrifuged pellet of HS had less sensitizing activity than the supernatant, but the antigen was removed completely by 0.22 micron filters and to some extent by 0.45 micron filters; it was minimally affected by sonication; it was destroyed by the action of Pronase but not by DNAase I when a kallikrein inactivator was added and the mixture incubated; incubation with DNAase II had no effect. Thus the presence of DNA was not required for the sensitizing activity of HS and the antigens recognized by antibodies in HS in ELISA were directed to its protein component. Strong reactions were given in immunoblotting of HS from BHV1 infected tissue cultures with anti-BHV1 glycoprotein monoclonal IgG, but HS from uninfected tissue cultures did not react with the same monoclonal IgG.     

Nuclear DNAase of the yeast Candida tropicalis

Using stepwise extraction of chromatin from Candida tropicalis by NaCl (0.1-1.0 M) the protein dissociated by 0.3 and 0.6 M NaCl (fractions 0.3 and 0.6) possessing the DNAase activity were obtained. These DNAases are activated by Mg2+ and cause preferential hydrolysis of heat-denaturated DNA. Fraction 0.3 DNAase has a maximum at neutral values of pH (around 7.0) and causes endonucleolytic hydrolysis of DNA. Fraction 0.6 DNAase causes exonucleolytic hydrolysis of DNA but a maximum at alkaline pH (8.0). The properties of isolated chromatin DNAases of Candida tropicalis differ from those of the known DNAases of the yeast Saccharomyces cerevisiae.     

Detection and characterization of IgG-and sIgA-abzymes capable of hydrolyzing histone H1

Immunoglobulins IgG and sIgA actively hydrolyzing histone H1 have been detected on analyzing proteolytic activity of antibodies isolated by chromatography on Protein A-agarose from blood serum of patients with multiple sclerosis and from colostrum of healthy mothers. These antibodies hydrolyze other histones less actively and virtually failed to cleave lysozyme of chicken egg. By gel filtration at acidic pH and subsequent analysis of protease activity of chromatographic fractions, it was shown that IgG and sIgA molecules were responsible for hydrolysis of histone H1. Anti-histone H1 antibodies of IgG and sIgA classes were purified by affinity chromatography on histone H1-Sepharose from catalytically active antibody preparations. The protease activity of anti-histone H1 IgG antibodies was inhibited by serine proteinase inhibitors, whereas anti-histone H1 sIgA antibodies were insensitive to inhibitors of serine, asparagine, and cysteine proteases.     

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.     

Blood-Derived RNA- and microRNA-Hydrolyzing IgG Antibodies in Schizophrenia Patients

Abzymes with various catalytic activities are the earliest statistically significant markers of existing and developing autoimmune diseases (AIDs). Currently, schizophrenia (SCZD) is not considered to be a typical AID. It was demonstrated recently that antibodies from SCZD patients efficiently hydrolyze DNA and myelin basic protein. Here, we showed for the first time that autoantibodies from 35 SCZD patients efficiently hydrolyze RNA (cCMP > poly(C) > poly(A) > yeast RNA) and analyzed site-specific hydrolysis of microRNAs involved in the regulation of several genes in SCZD (miR-137, miR-9-5p, miR-219-2-3p, and miR-219a-5p). All four microRNAs were cleaved by IgG preparations (n = 21) from SCZD patients in a site-specific manner. The RNase activity of the abzymes correlated with SCZD clinical parameters. The data obtained showed that SCZD patients might display signs of typical autoimmune processes associated with impaired functioning of microRNAs resulting from their hydrolysis by the abzymes.     

A simple method for elimination of RNAase contamination from DNAase preparations

RNAase which usually contaminates commercial pancreatic DNAase preparations can be removed by affinity chromatography on agarose-coupled anti-RNAase antibodies. RNA treated with purified DNAase can be re-isolated intact, as determined by polyacrylamide gel electrophoresis under denaturing conditions. This method might be applicable to purification of other preparations which are used in RNA research, such as PNPase (polynucleotide phosphorylase) and specific antibodies for polysome immunoprecipitation. The non-specific binding of DNAase in our system is less than 5% and the loss of specific activity of DNAase I is less than 1%.     

Diversity of integrase-hydrolyzing IgGs and IgMs from sera of HIV-infected patients

It was previously shown that small fractions of IgGs and IgMs from the sera of AIDS patients specifically hydrolyze only HIV integrase (IN) but not many other tested proteins. Here we present evidence showing that these IgGs and IgMs are extreme catalytically heterogeneous. Affinity chromatography on IN-Sepharose using elution of IgGs (or IgMs) with different concentration of NaCl and acidic buffer separated catalytic antibodies (ABs) into many AB subfractions demonstrating different values of K _m for IN and k _cat. Nonfractionated IgGs and IgMs possess serine-, thiol-, acidiclike, and metal-dependent proteolytic activity. Metal-dependent activity of abzymes increases in the presence of ions of different metals. In contrast to canonical proteases having one pH optimum, initial nonfractionated IgGs and IgMs demonstrate several optima at pH from 3 to 10. The data obtained show that IN-hydrolyzing polyclonal IgG and IgM of HIV-infected patients are cocktails of anti-IN ABs with different structure of the active centers possessing various affinity to IN, pH optima, and relative rates of the specific substrate hydrolysis.     

Special Features of the DNA-Hydrolyzing Activity of the Antibodies in Systemic Lupus Erythematosus

Two types of IgG anti-DNA antibodies exhibiting DNA-hydrolyzing activity have been isolated from blood serum of patients with systemic lupus erythematosus. This DNase activity of antibodies differs from serum DNases by the non-processive mode, temperature resistance, pH optimum, and the rate of DNA hydrolysis. It is suggested that the anti-DNA antibody molecule possessing DNase activity contains two sites: one site determines specificity of antibody-DNA interaction, whereas the other is responsible for manifestation of the catalytic activity.     

Immunoglobulin subclasses of antibodies to human T-cell leukemia/lymphoma virus I-associated antigens in acquired immune deficiency syndrome and lymphadenopathy syndrome

Immunoglobulin G (IgG) and IgM antibodies to human T-cell leukemia/lymphoma virus-I (HTLV-I)-associated membrane antigens (HTLV-I-MA) were assayed by indirect cytospin immunofluorescence, and IgG and IgM antibodies to purified HTLV-I were assayed by enzyme-linked immunosorbent assay in sera from 119 immunologically well-characterized promiscuous male homosexuals in The Netherlands, of whom 9 suffered from acquired immune deficiency syndrome (AIDS), 18 suffered from lymphadenopathy syndrome (LAS), and 5 suffered from gay bowel syndrome. Antibodies to HTLV-I-MA were present in four of nine AIDS patients, including one patient with antibodies to purified HTLV-I. Antibodies to HTLV-I-MA were present in 6 of 18 LAS patients, including 3 patients with antibodies to purified HTLV-I. Of five patients with gay bowel syndrome, one had IgG and IgM antibodies to HTLV-I-MA. Of the four HTLV-I seropositive AIDS patients, two had IgG and IgM antibodies to HTLV-I or HTLV-I-MA, one had only IgG antibodies, and one had only IgM antibodies. Of the six HTLV-I seropositive LAS patients, four had IgG and IgM antibodies to HTLV-I or HTLV-I-MA, and two had only IgM antibodies. In the sera from 27 healthy homosexuals with and 60 without T-cell subset imbalances, no antibodies to HTLV-I or HTLV-I-MA were detected.     

Impact and intracellular localization of antibodies to DNA in MDCK cells

A study was performed with liquid chromatography of highly purified antibodies to DNA of IgG from blood serum of healthy donors-SLE or RA patients and their clinically healthy relatives. It was shown that, depending on the pathology, these antibodies were distinguished by DNA—hydrolyzing activity. These antibodies were incubated with MDCK cells. It was found that they were mostly localized in the vicinity of the nucleus and affected the cellular morphology, number of viable cells, and chromatin of MDCK cells differently. The biological role of antibodies to DNA is discussed.     

Studies on DNA repair in Bacillus subtilis. III. Identification of an exonuclease which enhances the priming activity of gamma-irradiated dna by "cleaning' damaged ends.

An enzyme which enhances the priming activity of gamma-irradiated DNA for type I DNA polymerase (EC 2.7.7.7) was identified and partially purified from extracts of Bacillus subtilis cells. The enzyme preferentially degraded gamma-irradiated DNA into acid-soluble materials. DNA preparations treated with heat, ultraviolet light, pancreatic DNAase (EC 3.1.4.5) or micrococcal DNAase (EC 3.1.4.7) were not susceptible to the enzyme. However, sonication rendered DNA susceptible to the enzyme to some extent. From these results, it is supposed that this enzyme may function by 'cleaning' damaged terminals produced by gamma-irradiation to serve as effective priming sites for repair synthesis by the type I DNA polymerase.     

A human monoclonal IgG1 with anti-idiotypic activity against anti-human thyroglobulin autoantibody

Sixty-one human myeloma proteins (HMP) from patients with multiple myeloma and Waldenstr?m macroglobulinemia were tested for anti-idiotypic (Id) activity against autoantibodies to double-stranded DNA, small nuclear ribonucleoproteins, and human thyroglobulin (HTg), by competitive radioimmunoassays and enzyme immunoassays. An IgG1, lambda HMP from patient BEN with anti-Id activity against antibodies to HTg is reported. IgG1 BEN was not directed toward human Fc fragments and its activity was not related to allotypic determinants. IgG1 BEN molecules recognized Id determinants (idiotopes) on F(ab')2 anti-HTg fragments, but not idiotopes of F(ab')2 fragments of antibodies of other specificities. This observation supports the general significance of Id network interactions in regulation and diversification of immune responses in man.     

Methods for limiting the action of SP3 DNAase and for the determination of the direction of hydrolysis of processive exonucleases.

The action of the exonuclease SP3 DNAase is inhibited by chemical modification of DNA with the cation N-cyclohexyl-N'-beta-(4-methylmorpholinium)-ethylcarbodiimide (CME). The limited activity of the enzyme on CMA-modified DNA makes it possible to demonstrate that the enzyme also initiates its attack on polydeoxyribonucleotides at the 5'-termini. This was determined by the analysis of the products from the digestion of CME-modified DNA containing labeled 5'-terminal phosphate groups. Such procedure can be adopted as a general approach for the determination of the direction of hydrolysis of other processive exonucleases. SP3 DNAase has been shown able to degrade oligo- and polydeoxyribonucleotides with or without 5'-terminal phosphate groups with equal efficiency (Aposhian, H.V., Friedman, N., Nichihara M., Heimer, E.P., and Nussbaum, A.L. (1970) J. Mol. Biol. 49, 367-379). The present work also shows that the enzyme can even hydrolyze oligo- and polynucleotides containing derivatized phosphate groups.