Autoantibodies unmasked by redox reactions

McIntyre, John A.; Wagenknecht, Dawn R.; Faulk, W. Pagé

doi:10.1016/j.jaut.2005.03.005

Cited by 60 publications

(65 citation statements)

References 28 publications

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“…14 We have determined from dose-response experiments that as little as a 28 lM hemin can yield significant unmasking of aPL from the mAb, Remicade (data not shown). In addition, evidence that the in vitro experimental conditions employed actually induced oxidation of Ig have been published, 6 in which it was shown that these conditions resulted in the oxidation of antibody tyrosine to nitrotyrosine by hemin oxidation.…”

Section: Resultsmentioning

confidence: 99%

“…6 Briefly, for EMF oxidation a 250 ll aliquot of mAb (250 lg/ml) in TRIS was exposed to 8 V for 10 sec. Hemin (Sigma, St. Louis, MO) was dissolved in 1.0 N NaOH (15.15 mg/ml).…”

Section: Methodsmentioning

confidence: 99%

“…9 It was shown that hemin was responsible for oxidation of the antibody because (i) none of the antibody changes occurred in the absence of hemin, (ii) none of the antibody changes occurred in the presence of hemopexin, which is a biological inhibitor of hemin, and (iii) ascorbic acid, which is an antioxidant, inhibited the hemin-mediated oxidative changes in a dose-response manner. 6 Briefly, for EMF oxidation a 250 ll aliquot of mAb (250 lg/ml) in TRIS was exposed to 8 V for 10 sec. Hemin (Sigma, St. Louis, MO) was dissolved in 1.0 N NaOH (15.15 mg/ml).…”

Section: Methodsmentioning

confidence: 99%

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Autoantibody potential of cancer therapeutic monoclonal antibodies

McIntyre

Faulk

2010

Intl Journal of Cancer

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We and others have reported that multiple autoantibodies are unmasked in human polyclonal antibody preparations after exposure to physiological oxidizing agents (hemin) or electromotive force. We now have asked if oxidation unmasks autoantibody reactivities in monoclonal antibodies (mAb). To do this, we have studied 9 FDA approved mAb used therapeutically, including 4 chimeric, 4 humanized and 1 chemically modified chimeric Fab that were exposed to the physiological oxidizing agent hemin at 36°C for 20 hr. These mAb were studied for autoantibody activity to phospholipids and DNA before and after oxidation with hemin and found to develop autoantibody activities after oxidation, while retaining their original specificity as measured by mAb anti-glycophorin A binding of erythrocytes, CD 19 binding to B lymphocytes and anti-HLA-A29 binding to A29-positive lymphocytes. The finding that certain mAb have the potential to unmask autoantibody activities as a consequence of exposure to physiological redox reactions in vitro gives pause to our present understanding of the immunological basis of tolerance and concern for potential autoimmune side effects in patients receiving mAb for diagnosis or treatment.Genetic engineering is a growth strategy in the design and development of monoclonal antibodies (mAb) for clinical therapeutics, such as drug targeting in cancer chemotherapy.1,2 However, the clinical use of mAb has been associated with serious side effects, 3 presumably due to collateral damage from reactions with antigens of unintended targets. 4 Inasmuch as a tenant of the scientific basis for the clinical use of mAb is that they react only with one or a small number of closely related epitopes, 5 we asked if their specificities might be altered by exposure to physiological concentrations of physiological oxidants known to participate in physiological redox reactions. We posed this query due to our earlier reports of the unmasking of autoantibody activities in human blood as well as in purified IgG that had been exposed to such physiological redox reactions. 6 One might then ask why such redox-reactive antibodies exist. We have proposed that redox-reactive antibodies represent elements of the body's immune defense and surveillance network. 7 Recently, a similar explanation has been put forward by others. 8 In the following paragraphs, we present data indicating that autoimmune activities can be unmasked in solutions of FDA approved mAb of several different specificities and immunochemistries. Material and MethodsThe experimental design and techniques used in this study are the same as those used in our earlier report of the unmasking of autoantibody activity in human IgG following oxidation with physiological oxidants such as hemin 6 or by using electromotive force (EMF).9 It was shown that hemin was responsible for oxidation of the antibody because (i) none of the antibody changes occurred in the absence of hemin, (ii) none of the antibody changes occurred in the presence of hemopexin, which is a biological inhibitor ...

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Section: Resultsmentioning

confidence: 99%

“…6 Briefly, for EMF oxidation a 250 ll aliquot of mAb (250 lg/ml) in TRIS was exposed to 8 V for 10 sec. Hemin (Sigma, St. Louis, MO) was dissolved in 1.0 N NaOH (15.15 mg/ml).…”

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Autoantibody potential of cancer therapeutic monoclonal antibodies

McIntyre

Faulk

2010

Intl Journal of Cancer

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“…Recent findings suggest the existence of "redox-activated" autoantibodies that are not detectable by conventional immunoassays [173,174]. A possible mechanism responsible for unmasking them may requires nitrosylation of tyrosine residues in the hypervaraible or complementary determining region of Ig [175]. This concept has potential consequences in the understanding of the antiphospholipid antibodies syndrome, the opsonisation of aging erythrocytes and of their immune elimination [176].…”

Section: Igsmentioning

confidence: 99%

Oxidation of proteins: Basic principles and perspectives for blood proteomics

Barelli

Canellini

Thadikkaran

et al. 2008

Proteomics Clinical Apps

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Protein oxidation mechanisms result in a wide array of modifications, from backbone cleavage or protein crosslinking to more subtle modifications such as side chain oxidations. Protein oxidation occurs as part of normal regulatory processes, as a defence mechanism against oxidative stress, or as a deleterious processes when antioxidant defences are overcome. Because blood is continually exposed to reactive oxygen and nitrogen species, blood proteomics should inherently adopt redox proteomic strategies. In this review, we recall the biochemical basis of protein oxidation, review the proteomic methodologies applied to analyse redox modifications, and highlight some physiological and in vitro responses to oxidative stress of various blood components.

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“…This may influence their biological functions. Indeed, it has been observed recently that the in vitro exposure of polyclonal antibodies from healthy individuals to heme resulted in the appearance of new strong reactivities toward various autoantigens (22)(23)(24)(25). The molecular mechanisms responsible for the effects on heme on the antigen binding activity of Igs are not understood.…”

mentioning

confidence: 99%

Antibodies Use Heme as a Cofactor to Extend Their Pathogen Elimination Activity and to Acquire New Effector Functions

Dimitrov

Roumenina

Doltchinkova

et al. 2007

Journal of Biological Chemistry

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Various pathological processes are accompanied by release of high amounts of free heme into the circulation. We demonstrated by kinetic, thermodynamic, and spectroscopic analyses that antibodies have an intrinsic ability to bind heme. This binding resulted in a decrease in the conformational freedom of the antibody paratopes and in a change in the nature of the noncovalent forces responsible for the antigen binding. The antibodies use the molecular imprint of the heme molecule to interact with an enlarged panel of structurally unrelated epitopes. Upon heme binding, monoclonal as well as pooled immunoglobulin G gained an ability to interact with previously unrecognized bacterial antigens and intact bacteria. IgG-heme complexes had an enhanced ability to trigger complement-mediated bacterial killing. It was also shown that heme, bound to immunoglobulins, acted as a cofactor in redox reactions. The potentiation of the antibacterial activity of IgG after contact with heme may represent a novel and inducible innate-type defense mechanism against invading pathogens.

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Autoantibodies unmasked by redox reactions

Cited by 60 publications

References 28 publications

Autoantibody potential of cancer therapeutic monoclonal antibodies

Autoantibody potential of cancer therapeutic monoclonal antibodies

Oxidation of proteins: Basic principles and perspectives for blood proteomics

Antibodies Use Heme as a Cofactor to Extend Their Pathogen Elimination Activity and to Acquire New Effector Functions

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