Autoantibodies In Human Sera Research Articles

Association of autoantibody levels with different stages of age-related macular degeneration (AMD): Results from the population-based Gutenberg Health Study (GHS)

PurposeAnti-retinal autoantibodies are assumed to be associated with age-related macular degeneration (AMD). To our knowledge, this is the first evaluation of autoantibodies in human sera of participants with different stages of AMD in a large population-based, observational cohort study in Germany.MethodsThe Gutenberg Health Study (GHS) is a population-based, observational cohort study in Germany, including 15,010 participants aged between 35 and 74. Amongst others, non-mydriatic fundus photography (Visucam PRO NM™, Carl Zeiss Meditec AG, Jena, Germany) was performed. Fundus images of the first 5000 participants were graded based on the Rotterdam Eye Study classification. Sera of participants with AMD (n=541) and sera of age-matched participants without AMD (n=490) were analyzed by antigen-microarrays. Besides descriptive statistics, autoantibody-levels were compared by Mann-Whitney-U test and the associations of level of autoantibodies with AMD were calculated by logistic regression analysis. Likewise, possible associations of the autoantibodies and both clinical and laboratory parameters on AMD subjects were analyzed.ResultsAutoantibodies against transferrin (p<0.001) were significantly downregulated in participants with early AMD and soft, distinct drusen (≥63 μm) or pigmentary abnormalities only compared to Controls. Mitogen-activated protein kinase 3 (p=0.041), glutathione peroxidase 4 (p=0.048), clusterin (p=0.045), lysozyme (p=0.19), protein kinase C substrate 80K-H (p=0.02), heat shock 70 kDa protein 1A (p=0.04) and insulin (p=0.018) show a trend between Control and participants with early AMD and soft, distinct drusen (≥63 μm) or pigmentary abnormalities only.ConclusionsThis study contributes to a growing knowledge of autoantibodies in association with different AMD stages compared to controls in the context of a large population-based study in Germany. Especially autoantibodies against inflammatory proteins were downregulated in participants with early AMD and soft, distinct drusen (≥63 μm) or pigmentary abnormalities only.

Study of thyroid disorders in vitiligo.

Vitiligo, an acquired sometimes familial depigmentary disorder of the skin and hair that results from selective destruction of melanocytes or pigment cells. It is the single most important non-neo plastic disease that involves both the immune system and melanocytes which are subsequently destroyed and the affected area turns pale and becomes white. The prevalence of the disease is between 1% and 2% in general population. It is a prospective, randomized, and controlled study. Over 90 vitiligo patients attending Dermatology OPD and vitiligo clinic are enrolled in the study. About 35 apparently healthy, age and sex matched individuals are selected to serve as control. A prescribed proforma containing all the demographic data, relevant questionnaire were recorded for each and every case with brief clinical history suggestive of any thyroid disease as well as those referred by the clinicians. P value <0.05 is considered significant. The Quantitative Determination of Thyroglobulin (Tg) Autoantibodies in Human Serum or Plasma by a Microplate Enzyme Immunoassay. Vitiligo group, thirty four (37.78%) patients have clinical hypothyroidism while 9 (10%) patients have clinical hyperthyroidism. This difference in the distribution is statistically significant (P < 0.05) with a Chi-square value of 10.08. The data are entered, analyzed and computed with SPSS version 15 software and well-known statistical test like Chi-square, students' 't' test have been advocated wherever found applicable. P value <0.05 is considered significant. There is increased incidence of autoimmune thyroid diseases among vitiligo patients. The reason being vitiligo usually precedes the onset of thyroid dysfunction.

SCREENING OF THYROID AUTOANTIBODIES ANTI-TG, ANTI-TPO AND ITS CORRELATION WITH CLINICAL THYROID DISEASES IN VITILIGO IN THE NORTH-EASTERN REGION OF INDIA

Background and aims: Vitiligo is an acquired sometimes familial depigmentary disorder of the skin and hair that results from selective destruction of melanocytes or pigment cells. It is the single most important non-neo plastic disease that involves both the immune system and melanocytes which are subsequently destroyed and the affected area turns pale and becomes white. The precise cause of vitiligo is complex but some evidences are always suggesting that it is caused by a combination of autoimmune, genetic and environmental factors. Over half of the people with vitiligo have acquired some loss of pigment cells before the age of 20 years. The prevalence of the disease is between 1-2% in general population. Therefore, the present study is taken up to evaluate the prevalence of thyroid diseases in vitiligo patients. Methods:It is a prospective, randomized and controlled study. 90 vitiligo patients attending the Dermatology OPD and vitiligo clinic are enrolled in the study. Thirty five apparently healthy, age and sex matched individuals are selected to serve as control. A prescribed proforma containing all the demographic data, relevant questionnaire were recorded for each and every case with brief clinical history suggestive of any thyroid disease as well as those referred by the clinicians.interpretationsare made. P value &lt; 0.05 is considered significant. The Quantitative Determination of Thyroglobulin (Tg) Autoantibodies in Human Serum or Plasma by a Microplate Enzyme Immunoassay. Results:Vitiligo group, thirty four (37.78%) patients have clinical hypothyroidism while 9(10%) patients have clinical hyperthyroidism. This difference in the distribution is statistically significant (P&lt;0.05) with a chi-square value of 10.08. The datas are entered, analysed and computed with SPSS version 15 software and well known statistical test like Chi-square, students t test have been advocated wherever found applicable. The necessary interpretations are made. P value &lt; 0.05 is considered significant. Conclusion:There is increased incidence of autoimmune thyroid diseases among vitiligopatients. Various thyroid antibodies were detected in thyroid disorders, suggesting that these thyroid antibodies could act as sensitive markers for detection of early and subclinical autoimmune disorders of thyroid gland including Graves disease and Hashimotos thyroiditis. The reason beingvitiligo usually precedes the onset of thyroid dysfunction. Therefore, these thyroid autoantibodies specially anti-TPO, anti-TG should be included along with thyroid parameters TSH, T3,T4 in routine investigation of vitiligo, as association of vitiligo with autoimmune thyroid disease is very much common in the North - Eastern region of India.

Construction of a ternary nano-architecture based graphene oxide sheets, toward electrocatalytic determination of tumor-associated anti-p53 autoantibodies in human serum

Almost 13% of all death in the world is related to cancer. One of the major reasons for failing cancer treatment is the late diagnosis of the tumors. Thus, diagnosis at the early stages could be vital for the treatment. Serum autoantibodies, as tumor markers, are becoming interesting targets due to their medical and biological relevance. Among them, anti-p53 autoantibody in human sera is found to be involved in a variety of cancers. Regarding this issue, a novel and sensitive electrochemical biosensor for detection of anti-p53 autoantibody has been developed. For this purpose, a nanocomposite including thionine (as an electron transfer mediator)/chitosan/nickel hydroxide nanoparticles/electrochemically reduced graphene oxide (Th-CS-Ni(OH)2NPs–ERGO) as a support platform was fabricated on the surface of glassy carbon electrode via a layer-by-layer manner and characterized through common electrochemical and imaging techniques. Then, p53-antigen was immobilized on the nanocomposite and used in an indirect immunoassay with horseradish peroxidase (HRP)-conjugated secondary antibody and H2O2 as the substrate, following the typical Michaelis–Menten kinetics. Under optimized condition, two techniques, including differential Pulse Voltammetry (DPV) and Electrochemical Impedance Spectroscopy (EIS) as a label free technique, applied for the biomarker detection. The linear ranges and LODs were obtained 0.1–500 pg mL−1 and 0.001 pg mL−1 using DPV and 5–150 pg mL−1 and 0.007 pg mL−1 using EIS, respectively. Furthermore, the proposed biosensor displayed satisfying stability, selectivity, and reproducibility. According to the results, the presented protocol is promising to develop other electrochemical biosensors.

Glycan-specific IgG anti-IgE autoantibodies are protective against allergic anaphylaxis in a murine model

IgE causes anaphylaxis in type I hypersensitivity diseases by activating degranulation of effector cells such as mast cells and basophils. The mechanisms that control IgE activity and prevent anaphylaxis under normal conditions are still enigmatic. We aimed to unravel how anti-IgE autoantibodies are induced and we aimed to understand their role in regulating serum IgE level and allergic anaphylaxis. We immunized mice with different forms of IgE and tested anti-IgE autoantibody responses and their specificities. We then analyzed the effect of those antibodies on serum kinetics and their invitro and invivo impact on anaphylaxis. Finally, we investigated anti-IgE autoantibodies in human sera. Immunization of mice with IgE-immune complexes induced glycan-specific anti-IgE autoantibodies. The anti-IgE autoantibodies prevented effector cell sensitization, reduced total IgE serum levels, protected mice from passive and active IgE sensitization, and resulted in cross-protection against different allergens. Furthermore, glycan-specific anti-IgE autoantibodies were present in sera from subjects with allergy and subjects without allergy. In conclusion, this study provided the first evidence that in the murine model, the serum level and anaphylactic activity of IgE may be downregulated by glycan-specific IgG anti-IgE autoantibodies.

Multiplex label-free biosensor for detection of autoantibodies in human serum: Tool for new kinetics-based diagnostics of autoimmune diseases

A multiplex label-free biosensor is developed for diagnostics of autoimmune diseases by highly sensitive measuring in human serum both critical characteristics of autoantibody: concentration and native kinetic parameters that reflect autoantibody aggressiveness to the organism's tissues. The biosensor is based on the spectral-correlation interferometry and image processing of a microarray glass biochip, affordable to be single-used in medical applications. Simultaneous 25-min detection and activity characterization of several autoantibodies in the same serum sample have been demonstrated for anti-thyroglobulin (anti-TG) and anti-thyroid peroxidase (anti-TPO) as models. The biosensor offers extremely high sensitivity: limits of detection in serum are 1.7 IU/mL and 6 IU/mL for anti-TPO and anti-TG, respectively. The dynamic range covers the whole range of clinically relevant concentrations of the autoantibodies up to 1000 IU/mL. The developed method of characterization of autoantibody activity by recording the kinetics of their binding with free native antigens is based on autoantibody polyvalency. The measurements in clinical serum samples have shown that the native kinetic parameters are independent of concentration. The proposed biosensor and method of native kinetic registration can be used to develop new criteria for comprehensive diagnostics of autoimmune diseases, based not only on traditional measurements of concentration but also on quantitative evaluation of autoantibody aggressiveness. The developed method can be adapted to other label-free sensors such as those based on the surface plasmon resonance, optical waveguides, etc.

Estimation of Insulin and Glutamic Acid Decarboxylase Autoantibodies In Patients With Type 1 Diabetes Mellitus

Background:Diabetes mellitus is a chronic disease began when there is essential insufficiency of insulin that produces by the pancreas, sometimes by the incompetence of that insulin. Such as insufficiency lead to elevate blood glucose concentrations, that in sequence impairment many human body. There are two main types of this disease, our study will be on type 1diabetes mellitus. Type 1 diabetes which called insulin-dependent diabetes mellitus in this type the pancreas be unsuccessful to produce the insulin. Type1diabetes milltus progress commonly in children and young people, type 1 diabetes is described by presence of mixing autoantibodies against variation of insulin antigens, such as Insulin autoantibodies,Glutamic Acid Decarboxylase Autoantibodies. Objective:To estimate the most autoantibodies and assessment of HbA1c in type 1 DM. Patients and Methods: This study was conducted at in AL-kindy Teaching Hospital-Center of Endocrine glands and diabetes Mellitus For the period 1/7/2016 until 1/2/2017, The study included (75) individual divided into (50) diabetic patients( 25 female and 25 male) their ages ranging between 10-45 years and(25).Healthy persons (11 female and 14 male) and there was questions for each patient about( Age, Family history, Onset of disease\years).Quantative ELISA test for detection of circulating autoantibodies against Glutamic Acid DecarboxylaseزIndirect immunofluorescence test to detected insulin auto antibodies in human serum, and measurements level of HbA1c for each subjects. Results: The results of this study indicate importance of autoantibodies to identify a group of type 1 diabetes mellitus patients.This results showed significant difference in the prevalence of autoantibodies in diabetes mellitus type 1 patients (P0.05). Conclusion:There are many cases of Diabetes Mellitus identified by laboratory investigation only ; whom are asymptomatic, screening tests had supportive for quick detection and treatment.

Bioluminescent aptamer-based sandwich-type assay of anti-myelin basic protein autoantibodies associated with multiple sclerosis

Bioluminescent solid-phase sandwich-type microassay was developed to detect multiple sclerosis (MS)-associated autoantibodies in human sera. The assay is based on two different 2′-F-Py RNA aptamers against the target autoantibodies as biospecific elements, and Ca2+-regulated photoprotein obelin as a reporter. The paper describes elaboration of the assay and its application to 91 serum samples from patients with clinically definite MS and 86 ones from individuals healthy in terms of MS. Based on the receiver-operator curve (ROC) analysis, the chosen threshold value as clinical decision limit offers sensitivity of 63.7% and specificity of 94.2%. The area under the ROC curve (AUC) value of 0.87 shows a good difference between the groups under investigation. The likelihood ratio of 10.97 proves the diagnostic value of the assay and its potential as one of the laboratory MS-tests.

An ELISA for quantifying GPIHBP1 autoantibodies and making a diagnosis of the GPIHBP1 autoantibody syndrome

BackgroundAutoantibodies against GPIHBP1, the endothelial cell transporter for lipoprotein lipase (LPL), cause severe hypertriglyceridemia (“GPIHBP1 autoantibody syndrome”). Affected patients have low serum GPIHBP1 and LPL levels. We report the development of a sensitive and specific ELISA, suitable for routine clinical use, to detect GPIHBP1 autoantibodies in serum and plasma. MethodsSerum and plasma samples were added to wells of an ELISA plate that had been coated with recombinant human GPIHBP1. GPIHBP1 autoantibodies bound to GPIHBP1 were detected with an HRP-labeled antibody against human immunoglobulin. Sensitivity, specificity, and reproducibility of the ELISA was evaluated with plasma or serum samples from patients with the GPIHBP1 autoantibody syndrome. ResultsA solid-phase ELISA to detect and quantify GPIHBP1 autoantibodies in human plasma and serum was developed. Spiking recombinant human GPIHBP1 into the samples reduced the ability of the ELISA to detect GPIHBP1 autoantibodies. The ELISA is reproducible and sensitive; it can detect GPIHBP1 autoantibodies in samples diluted by >1000-fold. ConclusionWe have developed a sensitive and specific ELISA for detecting GPIHBP1 autoantibodies in human serum and plasma; this assay will make it possible to rapidly diagnose the GPIHBP1 autoantibody syndrome.

Label-free microarray-based detection of autoantibodies in human serum

Multiplex assays for autoantibodies have shown utility both in research towards understanding the basic biology of autoimmune disease, and as tools for clinical diagnosis. New label-free multiplex analysis methods have the potential to streamline both the process of assay development and assay workflow. We report fabrication and testing of a 5-plex autoantigen microarray using the Arrayed Imaging Reflectometry (AIR) platform. This label-free technology provides rapid, sensitive, and quantitative detection of an arbitrary number of analytes in a standard multiwell format. In this work, we demonstrate that AIR is able to detect antibodies to Ro60, La/SSB, Scl-70, BicD2, and Ro52 in single-donor human serum samples with multiplex results comparable to singleplex ELISA or Luminex assays.

Qualitative and Quantitative Assay for Detection of Circulating Autoantibodies against Human Aortic Antigen.

Increased amount of autoantibodies in human sera are the hallmark of autoimmune diseases ( Wang et al., 2015 ). In case of known antigen, detection of autoantibodies is done using laboratory based methods. However, in most autoimmune diseases, knowledge of self-antigen is still vague. We have developed an ELISA-based quantitative assay to detect the presence of autoantibodies as well as to measure the circulating autoantibodies in the sera of patients suffering from large vessel vasculitis (LVV), an autoimmune disease ( Chakravarti et al., 2015 ). Using this assay, we detected the increase in anti-aortic antibodies in LVV patient's sera. We have further verified the results by independent biochemical techniques and found the specificity to be > 94% ( Chakravarti et al., 2015 ). This method can be uniquely modified to suit any autoimmune, in particular organ specific, disease and thus has wider applications in the detection and quantification of autoantibodies.

Label-free piezoelectric biosensor for prognosis and diagnosis of Systemic Lupus Erythematosus

An autoantigen piezoelectric sensor to quantify specific circulating autoantibodies in human serum is developed. The sensor consisted on a quartz crystal microbalance with dissipation monitoring (QCM-D) where TRIM21 and TROVE2 autoantigens were covalently immobilized, allowing the selective determination of autoantibodies for diagnosis and prognosis of Systemic Lupus Erythematosus (SLE). The sensitivity of the biosensor, measured as IC50 value, was 1.51U/mL and 0.32U/mL, for anti-TRIM21 and anti-TROVE2 circulating autoantibodies, respectively. The sensor is also able to establish a structural interaction fingerprint pattern or profile of circulating autoantibodies, what allows scoring accurately SLE patients. Furthermore, a statistical association of global disease activity with TRIM21-TROVE2 interaction was found (n=130 lupic patient samples, p-value=0.0413). The performances of the biosensor were compared with standard ELISA and multiplex DVD-array high-throughput screening assays, corroborating the viability of piezoelectric biosensor as a cost-effective in vitro assay for the early detection, monitoring or treatment of rare diseases.

Sensitive array-based assay for determination of serological protein kinase A autoantibody levels based on its antigen protein activation

ObjectivesWe investigated the effect of cPKAα conformational states during protein immobilization on an array platform for cPKA autoantibody assays for sensitive and high-throughput profiling of protein kinase A (PKA) autoantibody levels in human sera. Design and methodsWe prepared activated human cPKAα protein arrays by addition of cofactors including ATP, MgCl2, and Triton X-100 to incubation buffer. Anti-human cPKAα antibody or PKA autoantibody levels in human sera were analyzed using activated human cPKAα protein arrays. ResultsActivation of cPKAα with ATP, Mg2+, and Triton X-100 enhanced the sensitivity of the assay by increasing the signal/noise ratio and lowering the limit of detection. cPKAα activation also enhanced the sensitivity of cPKA autoantibody detection in human sera. We successfully applied this assay to determine cPKA autoantibody levels in human sera from normal individuals (n=30) and hepatic cancer patients (n=30). ConclusionsOur results demonstrate that cPKAα activation enhanced the sensitivity of array-based PKA autoantibody assays, and that this assay is suitable for high-throughput analyses of cPKA autoantibodies in human sera.

Graphene oxide interfaces in serum based autoantibody quantification.

A reliable quantification of protein markers will undoubtedly underpin profound developments in disease surveillance, diagnostics, and improved therapy. Although there potentially exist numerous means of achieving this, electrochemical impedimetric techniques offer scale of sensitivity, cost, convenience, and a flexibility with which few alternatives can compete. Though there have been marked developments in electroanalytical protein detection, the demands associated with accessing the inherent assay sensitivity in complex biological media largely remains. We report herein the use of cysteamine-graphene oxide modified gold microelectrode arrays in underpinning the ultrasensitive and entirely label free non-faradaic quantification of Parkinson's-relevant autoantibodies in human serum.

Correction: A Rapid Lateral Flow Immunoassay for the Detection of Tyrosine Phosphatase-Like Protein IA-2 Autoantibodies in Human Serum

Correction: A Rapid Lateral Flow Immunoassay for the Detection of Tyrosine Phosphatase-Like Protein IA-2 Autoantibodies in Human Serum

A rapid lateral flow immunoassay for the detection of tyrosine phosphatase-like protein IA-2 autoantibodies in human serum.

Type 1 diabetes (T1D) results from the destruction of pancreatic insulin-producing beta cells and is strongly associated with the presence of islet autoantibodies. Autoantibodies to tyrosine phosphatase-like protein IA-2 (IA-2As) are considered to be highly predictive markers of T1D. We developed a novel lateral flow immunoassay (LFIA) based on a bridging format for the rapid detection of IA-2As in human serum samples. In this assay, one site of the IA-2As is bound to HA-tagged-IA-2, which is subsequently captured on the anti-HA-Tag antibody-coated test line on the strip. The other site of the IA-2As is bound to biotinylated IA-2, allowing the complex to be visualized using colloidal gold nanoparticle-conjugated streptavidin. For this study, 35 serum samples from T1D patients and 44 control sera from non-diabetic individuals were analyzed with our novel assay and the results were correlated with two IA-2A ELISAs. Among the 35 serum samples from T1D patients, the IA-2A LFIA, the in-house IA-2A ELISA and the commercial IA-2A ELISA identified as positive 21, 29 and 30 IA-2A-positive sera, respectively. The major advantages of the IA-2A LFIA are its rapidity and simplicity.

Electrochemical biosensor for quantitation of anti-DNA autoantibodies in human serum

Measurement of serum autoantibody is a critical tool in the diagnosis and management of autoimmune diseases. However, rapid and convenient methods at the point-of care have not been achieved in large part because any one antibody species is a heterogeneous and miniscule fraction of the total serum immunoglobulin displaying identical properties other than its antigen-binding specificity. The present system addresses these challenges by vacuum-mediated transport of diluted serum through an antigen-coated porous membrane. To measure anti-DNA autoantibodies, native DNA was immobilized into a poly(vinylidene fluoride) membrane pre-coated with a synthetic phenylalanine/lysine co-polymer. Flow-through of primary and peroxidase-conjugated secondary antibodies over the course of 3min enhanced productive antibody–antigen interactions by bringing the reactants into close mutual proximity. Signal was quantified electrochemically during the enzymatic conversion of the tetramethylbenzidine substrate to a charge-transfer complex. The electrochemical signals generated by sera from patients with systemic lupus erythematosus using this device showed good quantitative correlation with a standard enzyme-linked immunosorbent assay and displayed similar detection limits. Inter- and intra-assay variability and electrode uniformity were favorable as was a two-month test of the stability of the DNA-coated membrane. While refining the fluidics requirements of this biosensor will be needed, its capacity to quantify over the course of 30min anti-DNA antibodies in fresh human serum without background reactivity of normal serum makes this a promising technology as a point-of care device of clinical utility.

Natural IgG Autoantibodies Are Abundant and Ubiquitous in Human Sera, and Their Number Is Influenced By Age, Gender, and Disease

The presence of self-reactive IgG autoantibodies in human sera is largely thought to represent a breakdown in central tolerance and is typically regarded as a harbinger of autoimmune pathology. In the present study, immune-response profiling of human serum from 166 individuals via human protein microarrays demonstrates that IgG autoantibodies are abundant in all human serum, usually numbering in the thousands. These IgG autoantibodies bind to human antigens from organs and tissues all over the body and their serum diversity is strongly influenced by age, gender, and the presence of specific diseases. We also found that serum IgG autoantibody profiles are unique to an individual and remarkably stable over time. Similar profiles exist in rat and swine, suggesting conservation of this immunological feature among mammals. The number, diversity, and apparent evolutionary conservation of autoantibody profiles suggest that IgG autoantibodies have some important, as yet unrecognized, physiological function. We propose that IgG autoantibodies have evolved as an adaptive mechanism for debris-clearance, a function consistent with their apparent utility as diagnostic indicators of disease as already established for Alzheimer’s and Parkinson’s diseases.

Biosensor-based Binding Assay for Platelet-Derived Growth Factor Receptor-α Autoantibodies in Human Serum

Biosensors are versatile tools for monitoring molecular interactions. Herein, we report a novel assay designed to detect anti-platelet-derived growth factor receptor α (PDGFRα) autoantibodies in the serum of patients affected by systemic sclerosis (SSc), an autoimmune disease of the connective tissue. The assay was based on resonant mirror sensing, and used recombinant PDGFRα as molecular bait for anti-PDGFRα autoantibodies (IgG class). The selection and optimization of the analytical procedure required a preliminary investigation on the preservation of the native-like conformation of the receptor following the immobilization procedure. The PDGFRα-based biosensor was used to test IgG purified from sera of SSc patients and healthy controls (HC). The specificity and the reversibility of the interaction permitted a rapid analysis, a single detection test requiring only a few minutes. Remarkably, this assay could discriminate between SSc patients and HC. This receptor-based biosensor, based on the reversible interaction between a blocked macromolecule and soluble ligands, and with major advantages such as the rapidity, the reusability of the capturing surface and the low cost per single test, could represent a promising approach for the diagnosis of SSc and other diseases characterized by anti-receptor autoantibodies or other bioactive ligands to cellular receptors.

Secreted human Ro52 autoantibody proteomes express a restricted set of public clonotypes

Long-lived secreted autoantibody responses in systemic autoimmunity are generally regarded to be polyclonal and to express a diverse B-cell repertoire. Here, we have used a proteomic approach based on de novo sequencing to determine the clonality and V region structures of human autoantibodies directed against a prototypic systemic autoantigen, Ro52 (TRIM21). Remarkably, anti-Ro52 autoantibodies from patients with primary Sjögren’s syndrome, systemic lupus erythematosus, systemic sclerosis or polymyositis were restricted to two IgG1 kappa clonotypes that migrated as a single species on isoelectric focusing; shared a common light chain paired with one of two closely-related heavy chains; and were public in unrelated patients. Targeted mass spectrometry using these uniquely mutated V region peptides as surrogates detected anti-Ro52 autoantibodies in human sera with high sensitivity and specificity compared with traditional ELISA. Mass spectrometry-based detection of specific autoantibody motifs provides a powerful new tool for analysis of humoral autoimmunity.