IgG In Sera Of Patients Research Articles

Anti-Laminin β4 IgG Drives Tissue Damage in Anti-p200 Pemphigoid and Shows Interactions with Laminin α3 and γ1/2 Chains

Laminin β4 was recently identified as a structural component of the dermal-epidermal junction and autoantigen of anti-p200 pemphigoid. In this study, we provided further evidence of the pathogenic effect of anti-laminin β4 IgG and identified potential binding partners of laminin β4. We showed that laminin β4 immune complexes led to activation of normal leukocytes and dose-dependent ROS release. Using cryosections of normal skin, we demonstrated that anti-laminin β4 patient serum IgG but not anti-laminin γ1 IgG, which are also detectable in patients with anti-p200 pemphigoid, cause dermal-epidermal separation in the presence of leukocytes. Proximity ligation assay and indirect immunofluorescence staining suggested that laminin β4 localizes closely to laminin α3 and γ2 in primary keratinocytes. Subsequent coimmunoprecipitation experiments using epidermal extracts confirmed the interaction of laminin β4 with the α3 and γ2 chains and indicated additional affinity to laminin γ1. The laminin β4-α3/β4-γ1 protein complexes were also detected using mass spectrometry. In conclusion, this study showed that anti-laminin β4 IgG can exert tissue damage in the skin, supporting their pathogenic role in anti-p200 pemphigoid. Our data further provide strong evidence for an interaction of laminin β4 with laminin α3, whereas its association to the laminin γ1 and γ2 chains is ambiguous.

Antiphospholipid antibodies in patients with stroke during COVID-19: A role in the signaling pathway leading to platelet activation.

Several viral and bacterial infections, including COVID-19, may lead to both thrombotic and hemorrhagic complications. Previously, it has been demonstrated an "in vitro" pathogenic effect of "antiphospholipid" antibodies (aPLs), which are able to activate a proinflammatory and procoagulant phenotype in monocytes, endothelial cells and platelets. This study analyzed the occurrence of aPL IgG in patients with acute ischemic stroke (AIS) during COVID-19, evaluating the effect of Ig fractions from these patients on signaling and functional activation of platelets. Sera from 10 patients with AIS during COVID-19, 10 non-COVID-19 stroke patients, 20 COVID-19 and 30 healthy donors (HD) were analyzed for anti-cardiolipin, anti-β2-GPI, anti-phosphatidylserine/prothrombin and anti-vimentin/CL antibodies by ELISA. Platelets from healthy donors were incubated with Ig fractions from these patients or with polyclonal anti-β2-GPI IgG and analyzed for phospho-ERK and phospho-p38 by western blot. Platelet secretion by ATP release dosage was also evaluated. We demonstrated the presence of aPLs IgG in sera of patients with AIS during COVID-19. Treatment with the Ig fractions from these patients or with polyclonal anti-β2-GPI IgG induced a significant increase of phospho-ERK and phospho-p38 expression. In the same vein, platelet activation was supported by the increase of adenyl nucleotides release induced by Ig fractions. This study demonstrates the presence of aPLs in a subgroup of COVID-19 patients who presented AIS, suggesting a role in the mechanisms contributing to hypercoagulable state in these patients. Detecting these antibodies as a serological marker to check and monitor COVID-19 may contribute to improve the risk stratification of thromboembolic manifestations in these patients.

Inactivated genotype 1a, 2a and 3a HCV vaccine candidates induced broadly neutralising antibodies in mice

ObjectiveA prophylactic vaccine is needed to control the HCV epidemic, with genotypes 1–3 causing >80% of worldwide infections. Vaccine development is hampered by HCV heterogeneity, viral escape including protection of...

Diagnostic value of serum IgG by Eliza to detecting Mycobacterium tuberculosis, Original Article

Introduction: In developing countries, which is an endemic region in terms of tuberculosis, there is an urgent need for fast, accurate, and inexpensive serological testing. The aim of this study was to determine the diagnostic value of patient serum IgG antibodies by ELISA in the diagnosis of Mycobacterium tuberculosis. Method: This case-control study was performed on patients with pulmonary tuberculosis in 2017-2020. After selecting the case (n = 30) and control (n = 30) subjects according to inclusion criteria, their blood samples were obtained and analyzed in the reference laboratory by standard kits for immunoglobulin G against 16, 36, and 40 kDa antigens of mycobacterium tuberculosis. Results: The mean age of the subjects was 47.07 (15.57%). The majority of participants were 46 (51.1%) women. There was no significant difference between the two groups regarding sex and age. serological examination of patients with pulmonary tuberculosis showed 25 positive results and only 4 of the control group had a positive result. Sensitivity, specificity, positive and negative predictive values of serology test were 83.3%, 86.67%, 86.20% and 87.88% respectively. Conclusion: Despite the acceptable sensitivity of the serologic immunoglobulin G test, according to the statement of World health organization (WHO), it did not possess an acceptable specificity. It is recommended that a a wider range of different antigens to be studied also it is essential to evaluate the diagnostic value of the other immunoglobulins inpatient in different stages of the disease.

N-glycosylated IgG in patients with kidney transplants increases calcium/calmodulin kinase IV in podocytes and causes injury.

Transplant glomerulopathy (TG) is a major cause of late allograft loss. Increased urine podocin/creatinine ratio in TG signifies accelerated podocyte loss. The mechanisms that lead to podocyte injury in TG remain unclear. We report that IgG from kidney transplant recipients with TG, but not from those without TG, cause a reduction in the expression of nephrin, significant podocyte actin cytoskeleton, and motility changes. These changes are preceded by increased expression of calcium/calmodulin kinase IV (CAMK4). Mechanistically, we found that CAMK4 phosphorylates GSK3β (glycogen synthase kinase 3 beta), activates the Wnt pathway and stabilizes the nephrin transcriptional repressor SNAIL. Silencing neonatal Fc Receptor (FcRn) or CAMK4 prevented the podocyte-damaging effects of IgG from patients with TG. Furthermore, we show that removal of N-linked glycosyl residues from these IgG did not interfere with its entry into the podocytes but eliminated its ability to upregulate CAMK4 and cause podocyte injury. The translational value of these findings is signified by the fact that CAMK4 is increased in podocytes of patients with TG but not in those without TG despite other forms of renal dysfunction. Our results offer novel considerations to limit podocyte injury in patients with kidney transplants, which may lead to eventual glomerular destabilization and transplant glomerulopathy.

Association of serum immunoglobulin G level with peritonitis in patients undergoing peritoneal dialysis: An analytical study

Introduction: Peritonitis is one of the most common complications of peritoneal dialysis. On the other hand, reduced levels of immunoglobulins (Igs), mainly IgG, can increase the risk of infection in various pathologic conditions. Here, we aimed to determine the association of severity and frequency of peritonitis with serum IgG levels in peritoneal dialysis patients. Methods: 100 patients with chronic renal failure referred to Imam Reza Hospital, Tabriz, Iran, for peritoneal dialysis were included in the study. Serum IgG levels were measured in all of these patients at the beginning of the study and after six months of follow-up. In case of peritonitis, serum IgG levels were also measured, and samples were sent to Imam Reza Hospital laboratory for analysis. Results: 40 cases (40%) were women, and 60 cases (60%) were men with a mean age of 47 years. 24 cases (24.0%) had at least one episode of peritonitis during the study. Among those with peritonitis, 14 cases (60.9%) had at least one more peritonitis episode in the 6-month follow up. The mean serum IgG levels were 1079 mg/dl and 429 mg/dl at the beginning and after six months of follow up, respectively. The difference was shown to be statistically significant (P = 0.006). There was no correlation between serum IgG level reduction and peritonitis in these patients (P > 0.999). Conclusion: This study found reduced levels of serum IgG in patients undergoing peritoneal dialysis. However, it was not associated with increased risk of peritonitis in these patients.

Expression and characterization of the soluble form of recombinant mature HSV-2 glycoprotein G for use in anti-HSV-2 IgG serodiagnostic immunoassay

Herpes simplex virus type-2 (HSV-2) specific glycoprotein G (gG-2) is widely used as the antigen of choice for serodiagnosis of HSV-2. In order to develop an ELISA for serodetection of HSV-2 IgG in patient sera, the soluble form of the mature gG-2 antigen (mgG-2), gG283-649, was expressed using a baculovirus expression system. gG283-649 contains the complete extracellular domain of mgG-2 including the C-terminal region, which despite homology to gG-1, does not cross-react with HSV-1 antibodies present in HSV-1 positive patient sera. gG283-649 had increased performance compared to a previously described gG-2 fragment and showed high sensitivity and specificity in a method comparison with HerpeSelect 1 & 2 Immunoblot IgG, a commercially available FDA-cleared assay for serodetection of HSV-1 and 2 antibodies. A total of 234 clinical samples consisting of 134 high risk samples, including 45 samples from pregnant subjects, and a panel of 100 mixed diagnosis samples, spanning the measurable range were tested in the method comparison. Clinical sensitivity and specificity were determined to be 94.2% and 100%, respectively. We conclude that this soluble form of mgG-2 is a novel antigen of choice for developing an ELISA for type-specific serodiagnosis of HSV-2.

Relation of ?-Amylase Activity with Glucose and Anti-Gliadin IgA and IgG in Sera of Patients with Celiac Disease

Celiac disease (CD) is an inflammatory small intestinal disorder that can lead to severe villous atrophy, and malabsorption . Since the measurement of α-amylase activity is the most widely used biochemical test for the diagnosis of pancreatic and non pancreatic disease , therefore serum α-amylase were studied in the present study in an attempt to evaluate the usefulness of this enzyme in the diagnosis of celiac disease and its relationship with anti gliadin IgA and IgG and serum glucose . Thirty one patients with celiac disease were studied and compared with twenty four healthy individuals . Significant elevation of α-amylase activity , glucose and anti gliadin IgA and IgG were observed in the sera of patients with celiac disease compared with the control group . Also a significant positive correlation between α-amylase activity and anti gliadin IgG were found in the present study in the sera of patients with celiac disease while a non significant correlation were found between α-amylase activity and anti gliadin IgA and glucose in the sera of the same patients of celiac disease.
 Keywords:- α-amylase , anti – gliadin IgA , IgG , glucose , celiac disease .

Elevated serum anti-phosphatidylcholine IgG antibodies in patients with influenza vaccination-associated optic neuritis

IntroductionBecause the optic nerve is mainly comprised from phospholipids such as phosphatidylcholine, the association between optic neuritis, anti-phospholipids antibodies and vaccination was examined. SubjectsTwo female pediatric patients suddenly presented bilateral optic neuritis after administration of trivalent inactivated influenza vaccine. MethodsThese two patients and another 11 patients with central nervous system demyelinating diseases were examined these anti-phospholipids antibodies. And immune histopathology was examined using serum derived from a patient with optic neuritis. ResultsHigh serum titer of anti-phosphatidylcholine antibody levels were detected during acute phase in patients with optic neuritis. The patient's serum IgG antibodies were found to have stained the capillary endotheliums in the preserved autopsied optic nerve. Patients with optic neuritis had significantly elevated serum levels of anti-phosphatidylcholine antibody in comparison to the other patients without optic neuritis. ConclusionAnti-phosphatidylcholine antibodies may be one of the causes of optic neuritis.

Autoantibodies to CD59, CD55, CD46 or CD35 are not associated with atypical haemolytic uraemic syndrome (aHUS)

Autoantibody formation against Factor H (FH) is found in 7–10% of patients who are diagnosed with atypical haemolytic uraemic syndrome (aHUS). These autoantibodies predominately target the C-terminal cell binding recognition domain of FH and are associated with absence of FHR1. Additional autoantibodies have also been identified in association with aHUS, for example autoantibodies to Factor I. Based on this, and that there are genetic mutations in other complement regulators and activators associated with aHUS, we hypothesised that other complement regulator proteins, particularly surface bound regulators in the kidney, might be the target for autoantibody formation in aHUS. Therefore, we assayed serum derived from 89 patients in the Newcastle aHUS cohort for the presence of autoantibodies to CD46 (membrane cofactor protein, MCP), CD55 (decay accelerating factor, DAF), CD35 (complement receptor type 1, CR1; TP10) and CD59. We also assayed 100 healthy blood donors to establish the normal levels of reactivity towards these proteins in the general population. Recombinant proteins CD46 and CD55 (purified from Escherichia coli) as well as soluble CR1 (CD35) and oligomeric C4BP-CD59 (purified from eukaryotic cell media) were used in ELISA to detect high responders. False positive results were established though Western blot and flow cytometric analysis. After excluding false positive responders to bacterial proteins in the CD46 and CD55 preparations, and responses to blood group antigens in CD35, we found no significant level of patient serum IgG reactivity with CD46, CD55, CD35 or CD59 above that detected in the normal population. These results suggest that membrane anchored complement regulators are not a target for autoantibody generation in aHUS.

IgG Fc N-Glycosylation in Guillain–Barré Syndrome Treated with Immunoglobulins

Intravenous immunoglobulin (IVIg) is the treatment of choice for Guillain-Barré syndrome (GBS), an immune-mediated peripheral neuropathy causing rapidly progressive limb weakness and respiratory failure. The working mechanism of IVIg in autoimmune diseases has not been elucidated, but previous studies indicate that some anti-inflammatory effects may be mediated by the N-glycosylation of the Fc-portion of IgG. GBS is a model disease to investigate these effects because GBS is an acute and monophasic disorder usually affecting healthy persons, which is treated with a standard course of IVIg, although the clinical response is highly variable. In the current study, the N-glycosylation of the Fc-portion of serum IgG was investigated in patients with GBS before and after treatment with IVIg in relation to clinical course and outcome. Glycoforms of serum IgG1 and IgG2 were determined separately by liquid chromatography mass spectrometry. These IgG subclasses were purified from the serum of 174 GBS patients before and in 150 patients 2 weeks after standard IVIg treatment regimen. Treatment-naive GBS patients compared with age- and sex-matched controls had lower levels of galactosylation of IgG1 and IgG2. IVIg preparations contained relatively high levels of galactosylated and sialylated IgG Fc glycoforms compared with serum IgG in patients. Treatment with IVIg resulted in an increase in serum of the Fc-galactosylation and -sialylation of both IgG1 and IgG2. The extent of normalization in serum IgG Fc glycosylation varied between patients. Multiple logistic regression analysis showed that patients with persistent low IgG galactosylation and sialylation despite IVIg treatment had the most severe forms of GBS and needed ventilator support more often. Kaplan-Meier analysis showed that these patients also needed more time to be able to walk again compared with patients with a normalized IgG Fc glycosylation profile. In conclusion, our results suggest that serum IgG Fc glycosylation in GBS is related to disease severity and clinical recovery after IVIg and may help to develop new measures to monitor the efficacy of treatment.

Detection of IgG in sera of patients with schistosomiasis japonica by developing magnetic affinity enzyme-linked immunoassay based on recombinant 14-3-3 protein

Low intensity of Schistosoma infection is the current status in China after long time treatment with praziquantel, therefore more sensitive diagnostic methods are required now. In this study, a magnetic affinity enzyme-linked immunoassay (MEIA) based on the signal transduction protein 14-3-3 of Schistosoma japonicum (Sj14-3-3), was developed for detecting schistosomiasis. Sera of infected BALB/c mice were collected and analyzed with MEIA and ELISA. Both MEIA and ELISA based on Sj14-3-3 were further used to detect serum IgG in patients. Sera from 58 schistosomiasis-related patients with low-intensity infection, and 30 non-endemic negative controls, were collected to assess the assay. Six sera from paragonimiasis patients were used to analysis cross-reactions. Compared with ELISA, MEIA has a higher ratio of the mean positive value to the mean negative value (P/N) at the same dilution ratio in infected mice (3.71 vs 2.45). Similar results were observed in humans, higher P/N of MEIA compared to ELISA (3.57 vs 2.68). There was no cross-reaction with the sera of paragonimiasis patients detected by both MEIA and ELISA. Our studies suggested that MEIA based on recombinant Sj14-3-3 protein (rSj14-3-3) had the potential for the diagnosis of schistosomiasis.

Serum IgG levels in IV immunoglobulin treated chronic inflammatory demyelinating polyneuropathy

ObjectiveTo determine the variability of serum IgG in patients with chronic inflammatory demyelinating polyneuropathy (CIDP).MethodsAll 25 CIDP patients had active but stable disease and were treated with individually optimised fixed...

Enrichment of total serum IgG4 in patients with pemphigus

Pemphigus vulgaris (PV) and pemphigus foliaceus (PF) are potentially fatal blistering diseases caused by autoantibodies targeting desmoglein (Dsg) adhesion proteins. Previous studies have shown an IgG4 > IgG1 predominance of anti-Dsg antibodies in pemphigus; however, no studies have examined total serum IgG4 levels in pemphigus. IgG4 is induced by chronic antigen stimulation, which could occur with persistent skin blistering and potentially elevate the total serum IgG4 relative to other IgG subclasses in patients with pemphigus. The primary aim of the study was to quantitate total and Dsg-specific IgG subclasses in patients with pemphigus. IgG subclasses and Dsg-specific IgG1 and IgG4 were quantitated in patients with PV and PF, and in sera from age-matched controls using a subclass enzyme-linked immunosorbent assay. The effectiveness of IgG4 depletion in blocking IgG pathogenicity in PV was determined using a keratinocyte dissociation assay. Dsg-specific antibodies comprised a median of 7·1% and 4·2% of total IgG4 in patients with PV and PF, respectively, with eightfold and fourfold enrichment in IgG4 vs. IgG1. Total serum IgG4, but not other IgG subclasses, was enriched in patients with PV and PF compared with age-matched controls (P = 0·004 and P = 0·005, respectively). IgG4 depletion of PV sera reduced pathogenicity in a keratinocyte dissociation assay and showed that affinity-purified IgG4 is more pathogenic than other serum IgG fractions. Dsg-specific autoantibodies are significantly enriched in IgG4, which may explain the enrichment of total serum IgG4 in some patients with pemphigus. By preferentially targeting autoimmune rather than beneficial immune antibodies, IgG4-targeted therapies may offer safer treatment options for pemphigus.

L-MPZ, a Novel Isoform of Myelin P0, Is Produced by Stop Codon Readthrough

Myelin protein zero (P0 or MPZ) is a major myelin protein (∼30 kDa) expressed in the peripheral nervous system (PNS) in terrestrial vertebrates. Several groups have detected a P0-related 36-kDa (or 35-kDa) protein that is expressed in the PNS as an antigen for the serum IgG of patients with neuropathy. The molecular structure and function of this 36-kDa protein are, however, still unknown. We hypothesized that the 36-kDa protein may be derived from P0 mRNA by stop codon readthrough. We found a highly conserved region after the regular stop codon in predicted sequences from the 3'-UTR of P0 in higher animals. MS of the 36-kDa protein revealed that both P0 peptides and peptides deduced from the P0 3'-UTR sequence were found among the tryptic fragments. In transfected cells and in an in vitro transcription/translation system, the 36-kDa molecule was also produced from the identical mRNA that produced P0. We designated this 36-kDa molecule as large myelin protein zero (L-MPZ), a novel isoform of P0 that contains an additional domain at the C terminus. In the PNS, L-MPZ was localized in compact myelin. In transfected cells, just like P0, L-MPZ was localized at cell-cell adhesion sites in the plasma membrane. These results suggest that L-MPZ produced by the stop codon readthrough mechanism is potentially involved in myelination. Since this is the first finding of stop codon readthrough in a common mammalian protein, detailed analysis of L-MPZ expression will help to understand the mechanism of stop codon readthrough in mammals.

Hepatopancreatobiliary manifestations and complications associated with inflammatory bowel disease

Diseases involving the hepatopancreatobiliary (HPB) system are frequently encountered in patients with inflammatory bowel disease (IBD). Hepatobiliary manifestations constitute some of the most common extraintestinal manifestations of IBD. They appear to occur with similar frequency in patients with Crohn's disease or ulcerative colitis. HPB manifestations may occur in following settings: 1) disease possibly associated with a shared pathogenetic mechanism with IBD including primary sclerosing cholangitis (PSC), small-duct PSC/pericholangitis and PSC/autoimmune hepatitis overlap, acute and chronic pancreatitis related to IBD; 2) diseases which parallel structural and physiological changes seen with IBD, including cholelithiasis, portal vein thrombosis, and hepatic abscess; and 3) diseases related to adverse effects associated with treatment of IBD, including drug-induced hepatitis, pancreatitis (purine-based agents), or liver cirrhosis (methotrexate), and reactivation of hepatitis B, and biologic agent-associated hepatosplenic lymphoma. Less common HPB manifestations that have been described in association with IBD include autoimmune pancreatitis (AIP), IgG4-associated cholangitis (IAC), primary biliary cirrhosis (PBC), fatty liver, granulomatous hepatitis, and amyloidosis. PSC is the most significant hepatobiliary manifestation associated with IBD and poses substantial challenges in management requiring a multidisciplinary approach. The natural disease course of PSC may progress to cirrhosis and ultimately require liver transplantation in spite of total proctocolectomy with ileal-pouch anal anastomosis. The association between AIP, IAC, and elevated serum IgG4 in patients with PSC is intriguing. The recently reported association between IAC and IBD may open the door to investigate these complex disorders. Further studies are warranted to help understand the pathogenesis of HPB manifestations associated with IBD, which would help clinicians better manage these patients. An interdisciplinary approach, involving gastroenterologists, hepatologists, and, in advanced cases, general, colorectal, and transplant surgeons is advocated.

Central Tolerance Regulates B Cells Reactive with Goodpasture Antigen α3(IV)NC1 Collagen

Patients and rodents with Goodpasture's syndrome (GPS) develop severe autoimmune crescentic glomerulonephritis, kidney failure, and lung hemorrhage due to binding of pathogenic autoantibodies to the NC1 domain of the alpha3 chain of type IV collagen. Target epitopes are cryptic, normally hidden from circulating Abs by protein-protein interactions and the highly tissue-restricted expression of the alpha3(IV) collagen chain. Based on this limited Ag exposure, it has been suggested that target epitopes are not available as B cell tolerogens. To determine how pathogenic anti-GPS autoantibody responses are regulated, we generated an Ig transgenic (Tg) mouse model that expresses an Ig that binds alpha3(IV)NC1 collagen epitopes recognized by serum IgG of patients with GPS. Phenotypic analysis reveals B cell depletion and L chain editing in Tg mice. To determine the default tolerance phenotype in the absence of receptor editing and endogenous lymphocyte populations, we crossed Tg mice two generations with mice deficient in Rag. Resulting Tg Rag-deficient mice have central B cell deletion. Thus, development of Tg anti-alpha3(IV)NC1 collagen B cells is halted in the bone marrow, at which point the cells are deleted unless rescued by a Rag enzyme-dependent process, such as editing. The central tolerance phenotype implies that tolerizing self-Ag is expressed in bone marrow.

Clinical images: Three‐dimensional computed tomography imaging of tophaceous gout

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Abnormal glycosylation of serum IgG in patients with IgA nephropathy

We postulated that IgA nephropathy (IgAN) involved alterations of serum IgG. The present study was undertaken to elucidate changes in serum IgG oligosaccharide structure analysis and to assess the diagnostic usefulness of this analysis in IgAN. The subjects were 28 children who were definitively diagnosed as having IgAN on the basis of renal biopsy and who had not received treatment for this disease; 27 healthy children; 15 untreated adults definitely diagnosed as having IgAN; 5 patients with other nephropathies; and 61 healthy adults. Oligosaccharide analyses of IgG were performed by reverse-phase high-performance liquid chromatography (HPLC) developed by Takahashi and colleagues. In both the children and the adults, the peak area ratio of isomers with two different galactosyl-N-acetylglucosamine (Gal-GlcNAc) binding sites was significantly lower in the presence of IgAN than in the healthy subjects (P<0.05 in children and P<0.001 in adults). The ratio of Gal-free oligosaccharides to Gal-positive oligosaccharides did not differ according to the presence or absence of IgAN in children or in adults. The analysis of the oligosaccharide structure of serum IgG seems to be useful in diagnosing IgAN.

Relative Quantification of Experimental Data from Antigen Particle Arrays

Protein arrays typically consist of a capture protein on a matrix, e.g., glass slide, silicon chip, or coded microparticle (1). The latter minimizes steric constraints and enhances reaction kinetics (2). Microarray technologies have been used for detecting allergens (3) and cytokines (4). A primary advantage of microarray technologies over conventional immunoassays is the ability to multiplex assays. Currently, ELISA is the method of choice for autoantibody detection (5). This method, however, is labor-intensive and requires comparatively large sample and reaction volumes. Nonetheless, ELISAs are currently performed to aid differential diagnosis of certain autoimmune diseases. Dermatomyositis (6) is characterized by detection of anti-Jo-1 IgG in patient sera. Both anti-Sm and anti-RNP/Sm IgGs are indicative of systemic lupus erythematosus (7). The presence of anti-Scl70 IgGs aids diagnosis of systemic sclerosis (8). Anti-SSB and -SSA IgGs are present in systemic lupus erythematosus (9) or Sjogren syndrome (10). With microarray technologies, all these autoantibodies can be screened simultaneously. The Luminex particle array platform comprises a hundred microparticles, each possessing a distinct fluorescent signature generated by a blend of two internal fluorescent dyes. Capture protein is conjugated to the bead surface, to assay for the cognate entity within a single reaction vessel. The instrument includes a microfluidics system and two lasers. A 635 nm laser excites the red and infrared classifier fluorophores that form the particular signature of each bead set. The second laser (523 nm) excites phycoerythrin dye used as a molecular tag for detection. Detection of cytokines (11), cancer markers, and allergens (12) has been reported. Use of internal calibration curves for cytokine quantification has been documented (13), but with antigen arrays, quantification is more difficult because of the time and expense required for antibody synthesis. Where quantification of antibodies has been cited, competitive immunoassays are described that use labeled forms of the …