Analysis of human self-reactive antibody repertoires by quantitative immunoblotting

Current Understanding of Natural Antibodies and Exploring the Possibilities of Modulation Using Veterinary Models. A Review

Natural antibodies (NAb) are defined as germline encoded immunoglobulins found in individuals without (known) prior antigenic experience. NAb bind exogenous (e.g., bacterial) and self-components and have been found in every vertebrate species tested. NAb likely act as a first-line immune defense against infections. A large part of NAb, so called natural autoantibodies (NAAb) bind to and clear (self) neo-epitopes, apoptotic, and necrotic cells. Such self-binding antibodies cannot, however, be considered as pathogenic autoantibodies in the classical sense. IgM and IgG NAb and NAAb and their implications in health and disease are relatively well-described in humans and mice. NAb are present in veterinary (and wildlife) species, but their relation with diseases and disorders in veterinary species are much less known. Also, there is little known of IgA NAb. IgA is the most abundant immunoglobulin with essential pro-inflammatory and homeostatic properties urging for more research on the importance of IgA NAb. Since NAb in humans were indicated to fulfill important functions in health and disease, their role in health of veterinary species should be investigated more often. Furthermore, it is unknown whether levels of NAb-isotypes and/or idiotypes can and should be modulated. Veterinary species as models of choice fill in a niche between mice and (non-human) primates, and the study of NAb in veterinary species may provide valuable new insights that will likely improve health management. Below, examples of the involvement of NAb in several diseases in mostly humans are shown. Possibilities of intravenous immunoglobulin administration, targeted immunotherapy, immunization, diet, and genetic modulation are discussed, all of which could be well-studied using animal models. Arguments are given why veterinary immunology should obtain inspiration from human studies and why human immunology would benefit from veterinary models. Within the One Health concept, findings from veterinary (and wildlife) studies can be related to human studies and vice versa so that both fields will mutually benefit. This will lead to a better understanding of NAb: their origin, activation mechanisms, and their implications in health and disease, and will lead to novel health management strategies for both human and veterinary species.

Transfer of natural auto-antibodies via egg yolk in chickens divergently selected for natural antibodies binding keyhole limpet hemocyanin

Barcodes of natural auto-antibody (NAAb) profiles based on staining intensity of isotypes binding numbers of self-(tissue) antigen fragments were suggested as parameters for immune diversity, and related to genetic background and health status in man, rodents and poultry. Here, hens, eggs and hatchlings from chicken lines divergently selected and bred for high (H line) or low (L line) total natural antibodies (NAb) levels in plasma binding keyhole limpet hemocyanin (KLH) at 16 weeks of age were tested for their NAAb repertoire binding chicken liver homogenate (CLH) fragments using quantitative Western immunoblotting. The aims of this study were 1. to detect line differences between the H and L line adult hens, eggs and hatchlings for the IgM and IgG isotypes binding CLH fragments, 2. study the presence of NAAb of both isotypes in yolk and albumen, as well as in hatchlings to detect a maternal NAAb transfer route via the egg to the hatchling, and 3. study whether new self-antigen binding isotypes and idiotypes are present in the hatchling. NAAb binding CLH fragments were found in plasma of adult hens (both IgM and IgG), in yolk (IgG only), and hatchlings (mostly IgG, but low levels of IgM). Auto-profiles of IgM showed homogeneity, while IgG profiles were heterogenic between individual hens and individual hatchlings. Significant higher levels as indicated by staining intensity and number of stained CLH fragments were found in plasma of hens genetically selected for high levels of NAb binding KLH. Lines could be clustered based on their auto-profiles indicating that profiles of self-binding IgM and IgG antibodies are genetically based. Visual comparison, clustering and correlation of hens and their hatchlings showed similarities for the IgG, but not the IgM isotype, indicating maternal transfer of IgG NAAb via the yolk. The IgM profile in the hatchlings on the other hand might represent neonatal self-binding antibody formation. As a consequence, hatchlings initially depend for self-binding antibodies on maternal IgG provision during early life.

Genetic aspects of auto-immune profiles of healthy chickens

Auto-antibody profiles binding liver antigens differed between chicken lines divergently selected for specific antibody responses to SRBC, and were affected by ageing suggesting both genetic and environmental effects. Presence and levels of IgM and IgG antibodies binding chicken liver cell lysate (CLL) fragments in plasma at 5 weeks of age from 10 individual full sibs and their parents from 5 H_srbc and 5 L_srbc line families was studied to reveal genetic relations. Non-genetic maternal effects were studied by comparing auto-antibody profiles of 36 weeks old hens from 2 other unrelated lines with the profiles from their chicks at hatch. IgM and IgG antibodies from parents and progeny from both H_srbc and L_srbc lines bound CLL fragments. Significant line and generation differences and their interactions were found for both isotypes. Higher staining of CLL fragments was usually found for H_srbc line birds. Lines were clustered by auto-antibody profiles, but staining by birds of both lines in both generations was very individual for IgG and IgM. The current data with full sibs therefore not supported a genetic basis for auto-antibody profiles. IgG but not IgM auto-antibody profiles of chicks correlated with maternal auto-antibody profiles. The results suggest that the auto-antibody repertoire of healthy chickens is largely stochastically initiated and may be affected by environmental challenges during ageing, but genetic mechanisms may underlie staining intensity of individual bound CLL fragments. The present results suggest that identification of fragments or profiles to be used at early age for genetic selection for health traits is not feasible yet. Secondly, the IgM profile of neonatal chickens seems non-organised independent of the maternal profile, but the neonatal IgG profile is much more related with the maternal profile. Consequences of these findings for disease susceptibility or breeding for optimal health are discussed.

Immunization enhances the natural antibody repertoire

The role of immunization in the production of antibodies directed against immunogens is widely appreciated in laboratory animals and in humans. However, the role of immunization in the development of "natural antibodies" has not been investigated. Natural antibodies are those antibodies present without known history of infection or immunization, and react to a wide range of targets, including "cryptic" self-antigens that are exposed upon cell death. In this study, the ability of immunization to elicit the production of natural antibodies in laboratory rats was evaluated. Laboratory rats were immunized with a series of injections using peanut extracts (a common allergen), a high molecular weight protein conjugated to hapten (FITC-KLH), and a carbohydrate conjugated to hapten (DNP-Ficall). Significantly greater binding of antibodies from immunized animals compared to controls was observed to numerous autologous organ extracts (brain, kidney, liver, lung, prostate, and spleen) for both IgM and IgG, although the effect was more pronounced for IgM. These studies suggest that immunization may have at least one unforeseen benefit, enhancing networks of natural antibodies that may be important in such processes as wound repair and tumor surveillance. Such enhancement of natural antibody function may be particularly important in Western society, where decreased exposure to the environment may be associated with a weakened natural antibody repertoire.

Single amino acid fingerprinting of the human antibody repertoire with high density peptide arrays

The antibody species that patrol in a patient's blood are an invaluable part of the immune system. While most of them shield us from life-threatening infections, some of them do harm in autoimmune diseases. If we knew exactly all the antigens that elicited all the antibody species within a group of patients, we could learn which ones correlate with immune protection, are irrelevant, or do harm. Here, we demonstrate an approach to this question: First, we use a plethora of phage-displayed peptides to identify many different serum antibody binding peptides. Next, we synthesize identified peptides in the array format and rescreen the serum used for phage panning to validate antibody binding peptides. Finally, we systematically vary the sequence of validated antibody binding peptides to identify those amino acids within the peptides that are crucial for binding "their" antibody species. The resulting immune fingerprints can then be used to trace them back to potential antigens. We investigated the serum of an individual in this pipeline, which led to the identification of 73 antibody fingerprints. Some fingerprints could be traced back to their most likely antigen, for example the immunodominant capsid protein VP1 of enteroviruses, most likely elicited by the ubiquitous poliovirus vaccination. Thus, with our approach, it is possible, to pinpoint those antibody species that correlate with a certain antigen, without any pre-information. This can help to unravel hitherto enigmatic diseases.

Hypotheses of the origin of natural antibodies: a glycobiologist's opinion

It is generally accepted that the generation of antibodies proceeds due to immunization of an organism by alien antigens, and the level and affinity of antibodies are directly correlated to the presence of immunogen. At the same time, vast experimental material has been obtained providing evidence of antibodies whose level remains unchanged and affinity is constant during a lifetime. In contrast to the first, adaptive immunoglobulins, the latter are named natural antibodies (nAbs). The nAbs are produced by B1 cells, whereas adaptive Abs are produced by B2. This review summarizes general data on nAbs and presents in more detail data on antigens of carbohydrate origin. Hypotheses on the origin of nAbs and their activation mechanisms are discussed. We present our thoughts on this matter supported by our experimental data on nAbs to glycans.

Natural autoantibodies in Bos taurus calves during the first twelve weeks of life

Natural autoantibodies (NAAb) have a role in maintaining physiological homeostasis and prevention of infections, and have been found in mammalian species tested so far. Albeit NAAb levels rise with age, little is known about the origin, function, regulation and initiation of NAAb in young animals. The present study addressed the presence of IgM and IgG NAAb binding glutamate dehydrogenase (GD), carbonic anhydrase (CA), myosin (MYO) and transferrin (TRANS) from before drinking colostrum until the first 12 weeks of life in plasma of female calves. In addition, NAAb to these four self-antigens were also measured in colostrum and in plasma of their mothers during three weeks before calving. Titers of NAAb binding GD, CA, MYO and TRANS were detected in plasma of cows before calving, in colostrum, and in plasma of calves before and after drinking of colostrum. Levels of NAAb in colostrum were positively related with levels of NAAb in plasma of cows. Before colostrum intake, levels of NAAb in plasma of calves were not related with levels of NAAb in plasma of their mother but were influenced by parity of their mother. After colostrum intake, levels of NAAb in plasma of calves in the first week of life were positively related with levels of NAAb in colostrum. Low NAAb levels in colostrum were related with low NAAb in plasma of calves in the first week of life, but after two weeks of life the relation between colostrum and plasma of calves was absent. In conclusion, NAAb are already present in the unborn calf, and levels of neonatal NAAb during the early weeks of life are affected by levels of maternal NAAb obtained via colostrum.

Individual Restriction Of Fine Specificity Variability In Anti-GM1 IgG Antibodies Associated With Guillain-Barré Syndrome

Elevated titers of serum antibodies against GM1 ganglioside are associated with a variety of autoimmune neuropathies. Much evidence indicates these autoantibodies play a primary role in the disease processes, but the mechanism for their appearance is unclear. We studied the fine specificity of anti-GM1 antibodies of the IgG isotype present in sera from patients with Guillain-Barré syndrome (GBS), using thin-layer chromatogram-immunostaining of GM1, asialo-GM1 (GA1), GD1b and GM1-derivatives with small modifications on the oligosaccharide moiety. We were able to distinguish populations of antibodies with different fine specificity. Remarkably, individual patients presented only one or two of them, and different patients had different populations. This restriction in the variability of antibody populations suggests that the appearance of the anti-GM1 antibodies is a random process involving restricted populations of lymphocytes. With the origin of disease-associated anti-GM1 antibodies as a context, this finding could provide explanation for the “host susceptibility factor” observed in GBS following enteritis with GM1 oligosaccharide-carrying strains of Campylobacter jejuni.

Natural (auto)antibodies in calves are affected by age and diet

BACKGROUND

Natural autoantibodies (N(a)ab) were found in every species tested so far, and are likely important in maintaining homeostasis.

OBJECTIVES

(1) To determine N(a)ab in Bos taurus calves, (2) evaluate effects of diet and age on N(a)ab binding repertoires in calves, and (3) delineate bovine liver cell lysate (BLL) antigens related with variation in rumen score and body weight.

ANIMALS AND METHODS

Effects of age and diet on staining of BLL fragments by IgM and IgG antibodies in serum samples collected at 20 or at 26 weeks of age from bull calves either fed a restricted or ad libitum diet were analyzed using quantitative Western blotting. Correlations between fragments stained and grouping of calves were done by Principal Component Analysis (PCA). Redundancy analysis (RDA) was done to relate rumen score and body weight variation at slaughter at 27 weeks of age with stained BLL fragments.

RESULTS

In sera from all calves IgM and IgG antibodies binding BLL antigens were found. Corresponding fragments were stained, but quantitative differences in staining intensities were related to diet and age for both IgM and IgG. PCA revealed that age had a greater influence than diet on BLL fragment staining. RDA suggested that staining by IgM or IgG of specific BLL fragments was related with variation in rumen score and body weight.

CONCLUSIONS AND CLINICAL IMPORTANCE

Analyses of N(a)ab in serum could be a potential tool to estimate the health status of cattle, and be used to evaluate effects of husbandry practices.

Age and genetic selection affect auto-immune profiles of chickens

Specificity, antibody isotype distribution and levels, of natural autoantibodies (NAAb) may be potential informative parameters for immune mediated natural disease resistance, immune modulation, and maintenance of physiological homeostasis. In a previous study we detected IgM and IgG antibodies to liver antigens in plasma from 1 year old chickens. Auto-immune profiles directed towards liver antigens differed between chicken lines divergently selected for specific antibody responses to sheep red blood cells. In the present study we measured the presence and typed levels and antibody isotypes (IgG and IgM) of NAAb binding the 'auto-antigen' complex chicken liver cell lysate (CLL) in plasma samples obtained from chickens at 5 weeks and at 1-year of age, respectively, by quantitative western blotting. Extensive staining patterns of plasma antibodies binding CLL were found for both isotypes and at both ages in all birds. At both ages, IgM and IgG bound similar numbers of CLL antigens, which remained almost constant for IgM, whereas the number of IgG stained bands in time was enhanced. Significant differences of binding patterns of NAAb (stained antigen fragments of CLL and staining intensity) were detected between the three different chicken lines at both ages and between both ages, and lines could be clustered on the basis of their auto-antibody profile. The present results indicate that analysis of the plasma NAAb repertoire of poultry like in mammals could provide a way of distinguishing differences of immune competence (as reflected by the selection criterion of antibody responses) between individuals and lines, and could provide tools to select individual birds for health and other traits. The age-dependency of the auto-immune profile suggest that such profiles may also reflect immune maturation, which should be taken into account when relating an auto-immune profile with other traits.

The past, present, and future of immune repertoire biology - the rise of next-generation repertoire analysis

T and B cell repertoires are collections of lymphocytes, each characterized by its antigen-specific receptor. We review here classical technologies and analysis strategies developed to assess immunoglobulin (IG) and T cell receptor (TR) repertoire diversity, and describe recent advances in the field. First, we describe the broad range of available methodological tools developed in the past decades, each of which answering different questions and showing complementarity for progressive identification of the level of repertoire alterations: global overview of the diversity by flow cytometry, IG repertoire descriptions at the protein level for the identification of IG reactivities, IG/TR CDR3 spectratyping strategies, and related molecular quantification or dynamics of T/B cell differentiation. Additionally, we introduce the recent technological advances in molecular biology tools allowing deeper analysis of IG/TR diversity by next-generation sequencing (NGS), offering systematic and comprehensive sequencing of IG/TR transcripts in a short amount of time. NGS provides several angles of analysis such as clonotype frequency, CDR3 diversity, CDR3 sequence analysis, V allele identification with a quantitative dimension, therefore requiring high-throughput analysis tools development. In this line, we discuss the recent efforts made for nomenclature standardization and ontology development. We then present the variety of available statistical analysis and modeling approaches developed with regards to the various levels of diversity analysis, and reveal the increasing sophistication of those modeling approaches. To conclude, we provide some examples of recent mathematical modeling strategies and perspectives that illustrate the active rise of a "next-generation" of repertoire analysis.

Genetic and phenotypic selection affect natural (auto-) antibody reactivity of chickens

Specificity, antibody isotype distribution and levels of natural antibodies (NAb) may be potential informative parameters for immune mediated natural disease resistance, immune modulation, and maintenance of physiological homeostasis. A large proportion of mammalian NAb have affinity for or are directed against self-antigens; so called natural auto antibodies (N(A)Ab). In the present study we showed the presence and typed levels and isotypes (total immunoglobulins, IgG and IgM) of N(A)Ab in plasma binding the 'auto-antigen' complex chicken liver cell lysate (CLL) of one-year old chickens from different genotype and phenotype backgrounds by ELISA and quantitative Western blotting. Higher levels of N(A)Ab binding CLL were found in plasma from chickens genetically selected for high specific antibody responses. In all birds, extensive staining patterns of plasma antibodies binding CLL were found for all isotypes, with IgG binding the highest number of CLL antigens and also showing the highest variation in staining patterns between individuals. Patterns of IgM antibodies binding CLL appeared to be more similar in all lines. Significant differences of binding patterns of N(A)Ab (antigen fragments of CLL and staining intensity) were detected between the different chicken lines, and lines could be clustered on the basis of their auto-antibody profile. In addition, also individual differences within lines were found. The present results indicate that analysis of the levels and the N(A)Ab repertoire of poultry like in mammals could provide a new way of distinguishing differences of immune competence and immune maturation between individuals, and could provide tools to select birds for health traits, or optimize hygiene and husbandry procedures.

Compensatory T-cell regulation in unaffected relatives of SLE patients, and opposite IL-2/CD25-mediated effects suggested by coreferentiality modeling

In human systemic lupus erythematosus (SLE), diverse autoantibodies accumulate over years before disease manifestation. Unaffected relatives of SLE patients frequently share a sustained production of autoantibodies with indiscriminable specificity, usually without ever acquiring the disease. We studied relations of IgG autoantibody profiles and peripheral blood activated regulatory T-cells (aTregs), represented by CD4⁺CD25^bright T-cells that were regularly 70–90% Foxp3⁺. We found consistent positive correlations of broad-range as well as specific SLE-associated IgG with aTreg frequencies within unaffected relatives, but not patients or unrelated controls. Our interpretation: unaffected relatives with shared genetic factors compensated pathogenic effects by aTregs engaged in parallel with the individual autoantibody production. To study this further, we applied a novel analytic approach named coreferentiality that tests the indirect relatedness of parameters in respect to multivariate phenotype data. Results show that independently of their direct correlation, aTreg frequencies and specific SLE-associated IgG were likely functionally related in unaffected relatives: they significantly parallelled each other in their relations to broad-range immunoblot autoantibody profiles. In unaffected relatives, we also found coreferential effects of genetic variation in the loci encoding IL-2 and CD25. A model of CD25 functional genetic effects constructed by coreferentiality maximization suggests that IL-2-CD25 interaction, likely stimulating aTregs in unaffected relatives, had an opposed effect in SLE patients, presumably triggering primarily T-effector cells in this group. Coreferentiality modeling as we do it here could also be useful in other contexts, particularly to explore combined functional genetic effects.

Changes Related to Age in Natural and Acquired Systemic Self-IgG Responses in Malaria

Background. Absence of acquired protective immunity in endemic areas children leads to higher susceptibility to severe malaria. To investigate the involvement of regulatory process related to self-reactivity, we evaluated potent changes in auto-antibody reactivity profiles in children and older subjects living in malaria-endemic zones comparatively to none-exposed healthy controls. Methods. Analysis of IgG self-reactive footprints was performed using Western blotting against healthy brain antigens. Plasmas of 102 malaria exposed individuals (MEIs) from endemic zone, with or without cerebral malaria (CM) were compared to plasmas from non-endemic controls (NECs). Using linear discriminant and principal component analysis, immune footprints were compared by counting the number, the presence or absence of reactive bands. We identified the most discriminant bands with respect to age and clinical status. Results. A higher number of bands were recognized by IgG auto-antibodies in MEI than in NEC. Characteristic changes in systemic self-IgG-reactive repertoire were found with antigenic bands that discriminate Plasmodium falciparum infections with or without CM according to age. 8 antigenic bands distributed in MEI compared with NEC were identified while 6 other antigenic bands were distributed within MEI according to the age and clinical status. Such distortion might be due to evolutionary processes leading to pathogenic/protective events.

Serum IgG repertoire in clinically isolated syndrome predicts multiple sclerosis

Objective

We previously showed that serum IgG repertoires distinguished multiple sclerosis (MS) patients from healthy subjects and from patients with other inflammatory neurological diseases (OIND). We questioned whether the serum IgG repertoire of patients presenting a clinically isolated syndrome (CIS) could predict MS.

Methods

The global IgG immune responses against brain antigens in sera from 50 CIS patients were evaluated by immunoblotting. The IgG reactivities were compared with those from MS sera ( n = 82), healthy sera ( n = 27), and sera from OIND ( n = 42). A linear discriminant analysis (LDA) defined a score for each individual.

Results

About 78% of scores obtained from CIS patients were located in the “MS area.” During the follow-up (3.5 ± 1.3 years), 28 patients fulfilled the McDonald criteria for MS, 15 patients remained CIS, and 7 patients developed OIND. Among the patients with an LDA score in the “MS area,” 61.5% converted to MS.

Discussion

Our results suggest that a pathological distortion of the self-reactive IgG repertoire occurs early so that immunomodulating treatment should be started as early as possible; they also highlight the early involvement of B cells in the physiopathological process in MS.

Multistrip Western blotting to increase quantitative data output

The qualitative and quantitative measurements of protein abundance and protein modification states are essential in understanding their role in diverse cellular processes. Traditional Western blotting technique, though sensitive, is prone to produce substantial errors and is not readily adapted to high-throughput technologies. We propose a modified immunoblotting procedure, which is based on simultaneous transfer of proteins from multiple gel-strips onto the same membrane, and is compatible with any conventional gel electrophoresis system. As a result, the data output per single blotting cycle can readily be increased up to ten-fold. In contrast to the traditional "one protein detection per electrophoresis cycle", this procedure allows simultaneous monitoring of up to nine different proteins. In addition to maintaining the ability to detect picogram quantities of protein, the modified system substantially improves data accuracy by reducing signal errors by two-fold. Multistrip Western blotting procedure allows making statistically reliable side-by-side comparisons of different or repeated sets of data. Compared to the traditional methods, this approach provides a more economical, reproducible, and effective procedure, facilitating the generation of large amounts of high-quality quantifiable data.

Self-Reactivity in the Dimeric Intravenous Immunoglobulin Fraction

Therapeutic intravenous immunoglobulin (IVIg) preparations contain antibodies reflecting the cumulative antigen experience of the donor population. IVIg contains variable amounts of monomeric and dimeric IgG, but there is little information available on their comparative antibody specificities. We have isolated highly purified fractions of monomeric and dimeric IgG by size-exclusion chromatography. Following treatment of all fractions at pH4, analyses by immunodot and immunocytology on human cell lines showed a preferential recognition of autoantigens in the dimeric IgG fraction. Investigation of the HEp-2 cytoplasmic proteome by 2D-PAGE, Western blot, and subsequent identification of IVIg reactive spots by mass spectrometry (LC-MS/MS) showed that IVIg recognized only a restricted set of the total proteins. Similar experiments showed that more antigens were recognized by the dimeric IgG fraction, especially when the dissociated dimer fraction was used, as compared to its monomeric counterpart. These observations are consistent with idiotype-anti-idiotype masking of auto-specific Abs in the dimeric fraction of IVIg.

Dynamic stability in random and scale-free B-lymphocyte networks

One of the most intriguing features of the immune system is regulation: a limited response when perturbed repeatedly. We propose a minimal network model for immune regulation in a lymphocyte network containing two types of elements: B lymphocytes and ligands that bind to their receptors. Effective interactions between B cells, mediated by other components of the immune system can be excitatory or inhibitory. In our model, B cell clones and ligand species are represented by nodes, and interactions by links. We expect that, as in many complex systems, the connectivity distribution is broad, motivating study of the model on a scale-free network; for comparison we study the same dynamics on a random graph. We characterize the dynamics of the model and its response to perturbations. Our model reproduces several key features of immune system dynamics: regulation (saturation of response), and more rapid response upon repeated perturbation with the same agents. Our results suggest that a scale-free network of interactions contributes to the regulation and dynamics of the immune system.

Transition towards antigen-binding promiscuity of a monospecific antibody

Polyspecificity is defined as the ability of a given antibody molecule to bind a large panel of structurally diverse antigens. A fraction of circulating IgG in all healthy individuals acquires promiscuous antigen-binding activity only after a transient exposure to certain protein destabilizing factors. The molecular mechanisms of this phenomenon are not well understood. Exposures to protein destabilizing agents are common steps in immunoglobulin isolation and purification processes. We performed kinetic and thermodynamic analyses using surface plasmon resonance-based technique in order to characterize the interactions of a single mouse monoclonal antibody to its cognate antigen before and after induction of promiscuous antigen-binding activity. The obtained results, suggest that enhanced antigen binding activity induced by exposure to mild denaturing condition resulted from an increase in the structural flexibility of the antigen-binding site. Further pH and ionic strength-dependence analyses of the antibody/antigen interactions demonstrated that the transition to promiscuous antigen-binding was accompanied by a change in the type of non-covalent forces involved in the complex formation. Moreover, from this study, it is evident that an antibody molecule could use two distinct thermodynamic pathways for binding to the same antigen while retaining the same value of the binding affinity. The obtained results may contribute to the understanding of the molecular mechanisms that lay behind natural antibody polyspecificity.

Comparative study of the anti-inflammatory effect of two intravenous immunoglobulin preparations manufactured by different processes

Intravenous immunoglobulin (IVIG) is increasingly used in the treatment of diverse immune-mediated disorders. Since several preparations of IVIG are available for therapy, it is possible that different manufacturing processes might influence clinical efficacy of IVIG. An insight into the mechanisms of action of such different IVIG preparations is therefore necessary that will provide further guidelines for the utility of IVIG preparations in autoimmune and inflammatory diseases. Since endothelial cells (EC) influence the inflammatory process via production of cytokines, chemokines and expression of adhesive molecules, we analyzed the anti-inflammatory effect on EC of two IVIG preparations: caprylated IVIG (IVIG-C) versus solvent/detergent-treated IVIG (IVIG-SD) preparation. We found that both IVIG preparations inhibit in an equivalent manner, the expression of different pro-inflammatory factors such as IL-6, IL-8, GM-CSF, IL-1beta and TNF-alpha and the adhesion molecules ICAM-1 and VCAM-1. Our results thus suggest that the caprylate while inactivating the virus and enhancing the yield of IgG during IVIG formulation, does not modulate the immunomodulatory properties of IVIG at EC level and that the two preparations show similar anti-inflammatory effects.

Evidence that human autoimmune thrombocytopenia mediated by both immunoglobulin isotypes IgM and IgG is an independent disease entity

Autoimmune thrombocytopenic purpura (AITP) is a bleeding disorder caused by clonally restricted self-reactive antibodies with specificity for platelet glycoproteins. Anti-platelet autoantibodies in AITP mainly belong to the IgG class. The occurrence of anti-platelet autoantibodies of the IgM isotype has been reported, and AITP is partially mediated by antibodies of both isotypes, IgM and IgG. Using a technique of quantitative immunoblotting of immunoglobulins on self-tissues, followed by multiparametric statistical analysis of the data, we here demonstrate that patients with IgM- and IgG-mediated AITP are readily discriminated from patients with IgM-mediated AITP as well as from patients with IgG-mediated AITP at the basis of self-reactive antibody repertoires of isotypes IgM and IgG toward non-platelet antigens of human origin. Our data suggest that, in view of the important physiological functions of self-reactive antibody repertoires, human AITP mediated by both immunoglobulin isotypes IgG and IgM may be an independent disease entity. The role of autoantibody isotype for the pathophysiology of AITP might currently be underestimated, and diagnostic and therapeutic procedures in AITP might profit from considering autoantibody isotype more carefully.

Heritable factors shape natural human IgM reactivity to Ro60/SS-A and may predispose for SLE-associated IgG anti-Ro and anti-La autoantibody production

Systemic lupus erythematosus (SLE) is characterized by various IgG autoreactivities, among which anti-Ro/SS-A is particularly pathology-associated and early detectable. SLE also shows significant familial aggregation, but genetic factors are not well understood and remain controversial for disease-associated IgG. Here we report that IgM anti-Ro showed a uniquely high degree of heritability in a study of SLE-affected families. Unlike IgM anti-La or anti-dsDNA, IgM anti-Ro was also significantly correlated to IgG anti-Ro among SLE patients, as well as to IgG anti-La and anti-dsDNA. We conclude that largely genetically determined, thus natural IgM anti-Ro-bearing precursor B-cells, may be an important factor for class switching and determinant spreading in early phases of SLE pathogenesis. Furthermore, we found unexpected sex differences in isotype/specificity correlations among SLE-unaffected relatives and control subjects, which could help understand the strong gender bias associated with SLE. We propose that the study of such correlation structures may reveal characteristic spreading pathways relevant for human SLE.

Alterations of self-reactive antibody repertoires in HIV disease: An insight into the role of T cells in the selection of autoreactive B cells

Infection with human immunodeficiency virus (HIV) is characterized by a progressive depletion of CD4(+) T cells that parallels a dysfunction of the B cell compartment and a disturbed recognition of self-antigens. The relationship between T lymphocyte homeostasis and abnormalities in the selection of self-reactive B cells is not clear as yet. We have therefore compared repertoires of natural antibodies of healthy donors and of patients at various stages of HIV infection. The reactivity of IgM and IgG antibodies in plasma of healthy blood donors and of HIV-positive patients with high and low CD4(+) T cell counts was assessed by semi-quantitative immunoblotting using self-antigens extracted from normal human tissues. Repertoires of reactivites were compared between groups of individuals by means of multiparametric statistical analysis. We observed that repertoires of self-reactive IgM and IgG from HIV-seropositive patients exhibited significantly altered patterns of reactivity, as compared to those of healthy controls. Further, self-reactive repertoires of IgM and IgG of patients with high CD4(+) T cell counts differed significantly from those of patients with low CD4(+) T cell counts. A longitudinal analysis of self-reactive antibody repertoires of progressor and non-progressor patients suggested an influence of CD4(+) T cell counts on immunoglobulin reactivity toward self-antigens. These observations support the hypothesis that altered T cell/B cell interactions due to altered CD4(+) T cell help severely impact on the selection of self-reactive antibody repertoires and may contribute to the onset of pathological autoimmunity in HIV disease.

Evolution of self-reactive IgG antibody repertoires in patients with relapsing-remitting multiple sclerosis

We have previously demonstrated a distortion of self-reactive IgG antibody repertoires in patients with multiple sclerosis (MS) compared to controls, by immunoblotting assays, using human brain homogenates. The analysis of the immune profiles against human brain antigens allowed us to distinguish MS patients, and to associate a particular pattern of reactivity for each clinical form of MS. The aim of the present study was to evaluate the evolution of such patterns in patients with relapsing-remitting MS (RRMS). In a first step, we confirmed, by western blotting using human brains as source of antigens, the existence of specific repertoires of IgG reactivity in whole serum collected from healthy subjects (n = 32) and from untreated patients with RRMS (n = 56). In a second step, the evaluation of patterns was performed at baseline and 1 year later in untreated RRMS patients (n = 15), and in RRMS patients treated with IFN-beta (n = 41). In both groups, little change in IgG reactivity in whole serum was found. However, a higher degree of stability was noted in treated versus untreated patients (P < 0.01). Our results have showed a specific and relatively stable pattern of reactivity for each RRMS individual tested against brain antigens even after a 1-year treatment prevailing in treated patients suggesting that IFN-beta could stabilize IgG antibody repertoires.

Serum IgM, IgG and IgA block by F(ab')-dependent mechanism the binding of natural IgG autoantibodies from therapeutic immunoglobulin preparations to self-antigens

Natural polyreactive IgG autoantibodies are present in the plasma of healthy individuals and as a result in pooled therapeutic intravenous immunoglobulin (i.v.Ig) preparations. The spectrum of self-antigens to which these autoantibodies bind, their fate after intravenous infusion and their biological activity are not well understood. The identity of serum proteins that mask binding of natural autoantibodies to self-proteins is a matter of controversy. The spectrum of native serum proteins bound by i.v.Ig was analyzed by two-dimensional electrophoresis. The reactivity of i.v.Ig was directed mainly to circulating immunoglobulins. The binding of the IgG autoantibodies from i.v.Ig to native human liver antigens was blocked not only by a F(ab')2-dependent mechanism by circulating IgM and IgG (as has been previously suggested), but also by serum IgA. This control of anti-self reactivity may be inefficient in some autoimmune diseases.

Increased polyclonal immunoglobulin reactivity toward human and bacterial proteins is associated with clinical protection in human Plasmodium infection

Background

Polyclonal B-cell activation is well known to occur in Plasmodium infections, but its role in pathogenesis or protection remains unclear. However, protective properties of natural antibodies have previously been demonstrated in other contexts.

Methods

Sera from asymptomatic and symptomatic Plasmodium-infected subjects locally detected in a survey study in the Brazilian Amazon, and from unexposed and exposed but presently uninfected control subjects, were assayed by a standardized quantitative immunoblot method allowing simultaneous detection of IgG or IgM reactivity to a large number of parasite-unrelated proteins.

Results

In subjects free of coinfection with hepatitis B virus, IgG reactivity to human brain antigens and Escherichia coli proteins was strikingly enhanced in asymptomatic Plasmodium-infected individuals when compared to such with clinical malaria symptoms, or to uninfected control subjects. This difference was most characteristic for limited exposure times (less than ten years locally, or 20 years in endemic areas). It was more significant than a similar trend found for IgG to Plasmodium falciparum antigens, and unrelated to parasitaemia levels. Asymptomatic subjects with comparatively short exposure characteristically showed relatively elevated IgG versus IgM reactivity. Polyclonal IgG reactivity appears triggered by previous P. falciparum but not Plasmodium vivax malaria.

Conclusion

The observed difference in polyclonal antibody production seems related to intrinsic activation states of infected individuals, rather than to parasite-antigen specific immune responses. However, it appears influenced by preceding stimuli. This supports the idea that acquired clinical immunity may not exclusively depend on antigen-specific responses, but also on the individual polyclonal reaction.

The natural autoantibody repertoire and autoimmune disease

The incidence of autoimmune diseases has shown a significant increase in developed countries during the last 40 years. The cause of this increase is still unknown, and reliable methods for the detection of individuals at risk of developing autoimmune disease are not available yet. To explore new methods for the diagnosis and monitoring of autoimmune disease, we have studied the repertoire of natural autoantibodies (NA) and its relationship with autoimmune disease using large arrays of defined antigens. NA are found in healthy humans and mice, apparently in the absence of immunization with their target antigens. We used knock-out mice to demonstrate that the repertoire of NA is influenced by factors not directly related to antigenic stimulation such as endogenous levels of histamine. By studying strains of mice known to differ in their susceptibility to autoimmune disease, we could conclude that the repertoire of NA reflects the susceptibility to develop autoimmune disease. The study of the human repertoire of NA required the development of bio-informatic tools to overcome the variation introduced by individual differences in the genetic background and immune history. We found that human NA are organized in clusters that can differentiate healthy subjects from patients with type 1 diabetes mellitus, type 2 diabetes mellitus or Behçet's disease patients. The development of new tools to undertake large-scale NA analysis could also enhance our understanding of the immune system, and leave us in a better position to face the up-coming epidemics of autoimmune disorders.

Autoantibody repertoires to brain tissue in autism nuclear families

The hypothesis of an immune dysfunction in autism spectrum disorders has previously been put forward without, however, compelling evidence of a direct relation to its etiology or pathogenesis. To further understand if autoimmunity could play a significant role in autism, we analyzed autoantibody repertoires to brain tissue extract in the plasma of 171 autism children, their parents, and 54 controls, by quantitative immunoblotting. Multiparametric analysis revealed significant differences between patients and controls, and showed that one single reactivity in Section 32 of the blot had the most power to discriminate between these samples. Family correlation coefficients and heritability estimates did not provide any evidence that this reactivity was genetically determined. While the molecular weight of the target protein suggested that it might be an isoform of Myelin Basic Protein (MBP), inhibition assays with human MBP argued against this hypothesis. The study evidences the widespread occurrence of autoreactivities to brain tissue in autism patients, which may represent the immune system's neuroprotective response to a previous brain injury occurred during neurodevelopment. The molecular identification of the target protein in Section 32 will contribute to the understanding of the role of immune responses against brain antigens in autistic patients.

Demonstration of natural autoantibodies against the neurofilament protein α-internexin in sera of patients with endocrine autoimmunity and healthy individuals

Serum anti-pituitary antibodies (APAs) to cytosolic antigens have been found in association with autoimmune hypophysitis, idiopathic hypopituitarism, and other autoimmune endocrinopathies. Here, an immunoblot method was used to search for serum autoantibody (AAb) reactivities against pituitary antigens, including nuclear and cytoskeletal proteins, in six patients with idiopathic hypopituitarism, 60 patients with type 1 diabetes, nine patients with autoimmune polyglandular syndrome (APS) type 1, and in 74 healthy controls. Frequent patient serum IgG reactivity was observed against a 60 kDa human pituitary antigen, and the cross-reactive 62 kDa protein from rat brain was identified as alpha-internexin (alpha-INX) by proteomic methods. IgG and IgM AAbs to this neuron-specific type IV intermediate filament (IF) protein were found in most sera of patients with endocrine autoimmunity as well as healthy subjects with no significant differences in frequencies between the groups, but the levels of IgM alpha-INX AAbs were higher in patients with hypopituitarism as compared to healthy controls (P = 0.032, Mann-Whitney U-test). These findings suggest that alpha-INX AAbs are not specifically related to autoimmune endocrine diseases and most probably are a part of the natural AAb repertoire. This is the first demonstration of alpha-INX AAbs as one of the predominant neuronal IF AAbs in human sera.

Distortion of the Self-Reactive IgG Antibody Repertoire in Multiple Sclerosis as a New Diagnostic Tool

To date, none of the myelin-associated Ag targets definitively discriminates between the immune response observed in multiple sclerosis (MS) patients and healthy subjects. However, it has been shown recently that analysis of global immune Ab profiles such as natural autoantibody reactivities can help to distinguish between normal individuals and patients suffering from various immune diseases. The aim of our study was to compare the global IgG immune response against brain self-Ags in sera from 82 MS patients and 27 healthy subjects. The analysis of the immune profiles was performed by Western blotting, and data were subjected to linear discriminant analysis. Particular patterns of IgG reactivity were found in healthy subjects, Sjögren patients, and MS patients. Moreover, this approach separated the three clinical forms of MS with a high concordance rate with the clinical data (kappa value, 77.8%). Our study suggests, for the first time, that serum IgG Ab repertoires are able to distinguish MS patients. In addition, our data suggest that patterns of IgG reactivity could model the pathological processes underlying the various forms of MS. Further characterization of such discriminant Ags could provide useful information regarding their potent role in pathogenesis or regulatory processes in MS.

Autoreactive antibody repertoire is perturbed in atherosclerotic patients

In patients with clinical symptoms of coronary atherosclerosis, T cells are activated and directed to autologous proteins contained in the active plaques, suggesting that autoimmune responses may play a role in atherosclerosis progression. Organ-specific autoimmune diseases are sometimes accompanied by broad alterations of serum autoreactive antibody repertoires. We thus investigated antibody repertoires at a global level, using a technique of immunoblotting that allows for the quantitative screening of antibody reactivities in complex antibody mixtures toward a large panel of antigens derived from homologous tissue extracts, followed by multiparametric statistical analysis of the data. We analyzed the autoreactive IgG repertoire in 20 patients with documented coronary atherosclerosis and in 20 matched healthy controls. Total proteins from atherosclerotic carotid specimens and normal arterial tissues (target organs) and from kidney, liver, and stomach (non-target control organs) were used as panels of antigens. Patients had a significantly perturbed antibody repertoire and an enhanced autoreactivity of IgG to target and non-target organs, as compared with controls. Reactivity of purified IgG to plaque and normal artery proteins was greater in patients, but reactivity of IgG in the whole serum toward normal arterial tissue was lower than in controls; this suggests that, in patients, autoreactivity toward normal arteries is regulated by serum factors. Our data indicate that atherosclerotic patients develop a perturbed humoral immune response directed toward arterial proteins, which impacts on the overall autoreactive repertoire. These findings further substantiate that autoimmune processes take place in atherosclerosis and most likely influence disease progression.

Towards a better understanding of heterophile (and the like) antibody interference with modern immunoassays

BACKGROUND

Heterophile antibodies interfere with immunoassays. Understanding the nature and characteristics of these antibodies provides a format for better identifying and removing them. Growing evidence suggests many of these antibodies are natural antibodies. Very large number of tests are being performed with automated analyzers and there has been a problem with misdiagnosis due to interference. New commercial agents for blocking heterophile antibodies have been developed.

METHODS

Review of the immunology and methodological literature with critical interpretation of the findings.

CONCLUSIONS

Heterophile antibodies consist of natural antibodies and autoantibodies. Both types are usually weak antibodies that interfere by noncompetitive mechanisms. Based on very strong circumstantial evidence, we propose that natural antibodies account for most interference with automated immunoassays. In terms of false positive results, the interference rate is very low, about 99.95% accuracy. Specific blocking agents have some theoretical advantage over nonspecific blocking agents, but in actual practice, the very low false positive frequency makes it difficult if not impossible to statistically compare blocking agents or other assay modifications with adequate statistical power. In the absence of a technique that lends itself to automation for removing all immunoglobulins, it appears that infrequent heterophile interference cannot be avoided.

Red blood cell transfusions are associated with alterations in self-reactive antibody repertoires of plasma IgM and IgG, independent of the presence of a specific immune response toward RBC antigens

Immunization to allogeneic RBC antigens occurs in transfused patients, and may be associated with the development of RBC-destructive antibodies directed against autologous RBC. The present study investigates the effect of transfusion of allogeneic RBC on self-reactive antibody repertoires, independent of the presence of a specific immune response directed toward RBC antigens. Antibody repertoires of IgM and IgG in plasma of hematological patients prior to starting a transfusion regime and of hematological patients receiving regular transfusions of leukocyte-depleted RBC were analyzed using quantitative immunoblotting on a panel of antigens derived from tissue and cell extracts, followed by multiparametric statistical treatment of the data. Multiparametric statistical analysis discriminated between self-reactive antibody repertoires of patients prior to starting a transfusion regime and those receiving regular RBC transfusions (IgM, 0.0001 < P < 0.0244/IgG, 0.0002 < P < 0.0088, depending on the tissue extract), whereas antibody repertoires of plasma IgM and IgG toward bacterial antigens were similar between groups of patients (P > 0.05). We conclude that the challenge of the immune system with allogeneic RBC antigens influences self-reactive antibody repertoires of plasma IgM and IgG, independent of the presence of a specific immune response toward RBC antigens.

The prevalence of proteolytic antibodies against factor VIII in hemophilia A

BACKGROUND

Factor VIII inhibitors are IgG alloantibodies that arise during replacement therapy in 25 to 50 percent of patients with severe hemophilia A. The hydrolysis of factor VIII by anti--factor VIII antibodies has been proposed as a mechanism of inactivation of factor VIII.

METHODS

We purified IgG from patients with severe hemophilia A. The proteolytic activity of the antibodies was assessed by incubating the IgG with biotinylated human factor VIII and analyzing patterns of factor VIII cleavage by sodium dodecyl sulfate--polyacrylamide-gel electrophoresis and immunoblotting. The controls were normal human IgG and IgG purified from plasma of patients with hemophilia who did not have inhibitory antibodies.

RESULTS

Significant proteolytic activity was detected in IgG from 13 of 24 inhibitor-positive patients. No hydrolytic activity was detected in control antibodies of IgG from patients without inhibitors. The rate of hydrolysis of factor VIII by purified IgG correlated positively with the factor VIII--neutralizing activity of IgG in plasma (r2=0.67, P=0.029). Principal-component analysis of migration profiles of digestion fragments demonstrated the heterogeneity of the catalytic potential of factor VIII inhibitors among patients.

CONCLUSIONS

Proteolysis is a mechanism by which IgG antibodies against factor VIII can inactivate factor VIII.

Human IgG monoclonal anti-alpha(IIb)beta(3)-binding fragments derived from immunized donors using phage display

Previous studies of the immune response in polytransfused Glanzmann thrombasthenia (GT) patients and in autoimmune thrombocytopenic purpura (AITP) have relied on serum analysis and have shown the frequent development of Abs directed against the alpha(IIb)beta(3) integrin. However, little is known about the molecular diversity of the humoral immune response to alpha(IIb)beta(3) due to the paucity of mAbs issuing from these pathologies. We have isolated human IgG anti-alpha(IIb)beta(3) binding fragments using combinatorial libraries of single-chain IgG created from the B cells of a GT and an AITP patient, both with serum Abs. Ab screening was performed using activated platelets or activated alpha(IIb)beta(3)-expressing Chinese hamster ovary cells. Sequencing of selected phage Abs showed that a broad selection of genes from virtually all V gene families had been used, indicating the diversity of the immune response. About one-half of the V(H) and V(L) segments of our IgG anti-alpha(IIb)beta(3) fragments displayed extensive hypermutations in the complementarity-determining region, supporting the idea that an Ag-driven immune response was occurring in both patients. The H chain complementarity-determining region 3 analysis of phage Abs revealed motifs other than the well-known RGD and KQAGDV integrin-binding sequences. To our knowledge, our study is the first to illustrate multiple human IgG anti-alpha(IIb)beta(3) reactivities and structural variations linked to the anti-platelet human immune response. Human alpha(IIb)beta(3) Abs preferentially directed against the activated form of the integrin were further characterized because platelet alpha(IIb)beta(3) inhibitors are potential therapeutic reagents for treating acute coronary syndromes. Currently available alpha(IIb)beta(3) antagonists do not specifically recognize the activated form of the integrin.

Broad alterations of self-reactive antibody-repertoires of plasma IgM and IgG in B-cell chronic lymphocytic leukemia (B-CLL) and B-CLL related target-restricted autoimmunity

B-cell chronic lymphocytic leukemia (B-CLL) is characterized by a malignant CD5+ B-cell clone. The leukemic clone commonly expresses IgM antibodies exhibiting reactivity toward a wide range of self-antigens. However, B-CLL associated autoimmunity is typically restricted to self-antigens expressed by blood cells, and mediated by IgG autoantibodies of polyclonal origin. In the present study, we addressed the question whether self-reactive antibody repertoires of plasma IgM and IgG are disturbed by monoclonal immunoglobulins of B-CLL patients, and whether antibody repertoires of patients exhibiting B-CLL associated target-restricted autoimmune disease (AID) differ from those of B-CLL patients without AID. We investigated antibody repertoires at a global level, using a technique of quantitative immunoblotting that allows for the quantitative screening of antibody reactivities in complex antibody mixtures toward a large panel of antigens derived from homologous tissue extracts, followed by multiparametric statistical analysis of the data. We demonstrate that self-reactive antibody repertoires of plasma IgM and IgG are broadly altered in patients with B-CLL, that alterations in self-reactive antibody repertoires are not restricted to B-CLL patients exhibiting AID, and that target-restricted autoimmunity in B-CLL patients is associated with altered antibody repertoires not restricted to the target organ. We conclude that monoclonal alterations of immunoglobulin production in B-CLL are associated with broad defects of self-reactive antibody repertoires. Our observations suggest that the application of therapeutic IVIg preparations might influence B-CLL by restoring normal self-reactive antibody repertoires in plasma.

Altered antibody repertoires of plasma IgM and IgG toward nonself antigens in patients with warm autoimmune hemolytic anemia

Warm autoimmune hemolytic anemia (WAIHA) is characterized by an accelerated extravascular clearance of red blood cells (RBC) mediated by RBC-bound IgG autoantibodies. We have recently demonstrated significantly altered self-reactive antibody (Ab) repertoires of plasma IgM in WAIHA patients. The natural IgM Ab repertoire in plasma is critical in modulating both autoimmune and alloimmune responses. In the present study, we investigated IgM and IgG Ab repertoires of WAIHA patients toward nonself antigens (Ag) using a quantitative immunoblotting technique, followed by multiparametric statistical analysis of the data. We demonstrate significantly altered Ab repertoires of IgM and IgG toward nonself Ag in WAIHA patients. The reactivity of plasma IgM of WAIHA patients was reduced compared to that of healthy individuals, independent of administering an immunosuppressive therapy. We observed that an increase in reactivity of plasma IgM during clinical remission of the disease was associated with the development of allo-Ab toward RBC-antigens during RBC transfusions. Taken together, the data indicate altered Ab repertoires of plasma IgM and IgG toward nonself Ag in WAIHA patients. A broadly reduced reactivity of plasma IgM toward nonself Ag might influence the adaptive immune response in WAIHA patients.

Reconstitution of self-reactive antibody repertoires of autologous plasma IgM in patients with non-Hodgkin's lymphoma following myeloablative therapy

In healthy individuals, natural self-reactive antibody repertoires are restricted to a limited subset of autoantigens that is selected early in development and that remains invariant between individuals through aging. In the present study, we addressed the question of whether self-reactive antibody repertoires of plasma IgM change during high-dose chemotherapy (HDCT) with autologous blood stem cell support and whether antibody repertoires generated during immune reconstitution are similar to those present under physiological conditions. We followed the development of antibody repertoires in patients undergoing HDCT for the treatment of B-cell non-Hodgkin's lymphoma (NHL). Antibody repertoires were investigated by quantitative immunoblotting on whole tissue extracts as sources of self-antigens and by multiparametric statistical analysis of the data. We demonstrate that self-reactive antibody repertoires of plasma IgM of NHL patients prior to HDCT differ from those of healthy individuals, that they change during recovery of immune functions, and that antibody repertoires similar to those of healthy individuals are generated during immune reconstitution. We conclude that the mechanisms responsible for the selection of self-reactive repertoires of autologous plasma IgM during immune reconstitution after HDCT may follow those present under physiological conditions and that immune reconstitution may include a shift from altered toward normal patterns of self-reactivity.