Anaphylactic properties of mouse monoclonal IgG2a antibodies

Mouse monoclonal antibodies (10 hybridoma antibodies specific for soluble antigens, 8 hybridoma antibodies specific for H-2 $\text{K}\text{D}$ antigens, and 9 myeloma immunoglobulins, among which 5 had a known specificity) of the IgG1, IgG2a, IgG2b, IgG3, IgA, and IgM isotypes were studied for their ability to induce mouse mast cell degranulation in vitro, in the presence of specific antigen or after heat aggregation. Monoclonal IgG1 antibodies, as well as IgG2b, IgG3, IgA, and IgM behaved as polyclonal antibodies of corresponding classes: all IgG1 induced mast cell degranulation with typical characteristics of IgG-mediated anaphylactic reactions, whereas IgG2b, IgG3, IgA, and IgM did not. By contrast, 2 hybridoma IgG2a and 3 myeloma IgG2a induced intense mast cell degranulation that could not be explained by a contamination with IgG1 or IgG1-IgG2a hybrid molecules. IgG2a-mediated reactions were observed in four different situations: soluble antigen-hybridoma IgG2a complexes, specific H-2 antigen-bearing mast cells challenged with hybridoma IgG2a anti-H-2, heat-aggregated myeloma IgG2a, and soluble antigen-myeloma IgG2a complexes. The conclusion was reached that mouse mast cells could be activated by mouse monoclonal IgG2a antibodies through a noncytotoxic, complement-independent mechanism involving mast cell Fcγ receptors.     

The application of immunoperoxidase test for the detection of antibodies various classes (IgA, IgG and IgM) coating bacteria in urine

For the detection of bacteria coated with immunoglobulins in urine the monoclonal antibodies against human IgA, IgG and IgM conjugated with peroxidase were used. For comparison, the immunofluorescence technique was also employed. The results obtained by two methods revealed that immunofluorescence were less sensitive. It was found that bacteria were predominantly coated with IgA (41,9 +/- 22,4%) and IgG (34,1 +/- 15,3 %) immunoglobulins. The IgM antibodies were found rarely (12,8 +/- 8%).     

Anti-spike S1 IgA,anti-spike trimeric IgG,and anti-spike RBD IgG response after BNT162b2 COVID-19 mRNA vaccination in healthcare workers

BackgroundMost studies on immune response after coronavirus disease 2019 (COVID-19) vaccination focused on serum IgG antibodies and cell-mediated immunity, discounting the role of anti-SARS-CoV-2 neutralizing IgA antibodies in preventing viral infection. This study was aimed to quantify serum IgG and IgA neutralizing antibodies after mRNA COVID-19 vaccination in baseline SARS-CoV-2 seronegative healthcare workers.MethodsThe study population consisted of 181 SARSCoV-2 seronegative healthcare workers (median age 42 years, 59.7% women), receiving two doses of Pfizer COVID-19 vaccine BNT162b2 (Comirnaty). Serum samples were collected before receiving the first vaccine dose, 21 days (before the second vaccine dose) and 50 days afterwards. We then measured anti-spike trimeric IgG (Liaison XL, DiaSorin), anti-spike receptor binding domain (RBD) IgG (Access 2, Beckman Coulter) and anti-spike S1 subunit IgA (ELISA, Euroimmun). Results were presented as median and interquartile range (IQR).ResultsVaccine administration elicited all anti-SARS-CoV2 antibodies measured. Thirty days after the second vaccine dose, 100% positivization occurred for anti-spike trimeric IgG and anti-spike RBD IgG, whilst 1.7% subjects remained anti-spike S1 IgA negative. The overall increase of antibodies level ratio over baseline after the second vaccine dose was 576.1 (IQR, 360.7-867.8) for anti-spike trimeric IgG, 1426.0 (IQR, 742.0-2698.6) for anti-spike RBD IgG, and 20.2 (IQR, 12.5-32.1) for anti-spike S1 IgA. Significant inverse association was found between age and overall increase of anti-spike trimeric IgG (r=-0.24; p=0.001) and anti-spike S1 IgA (r=-0.16; p=0.028), but not with anti-spike RBD IgG (r=-0.05; p=0.497).ConclusionsmRNA COVID-19 vaccination elicits sustained serum levels of anti-spike trimeric IgG and anti-spike RBD IgG, while also modestly but significantly increasing those of anti-spike S1 IgA.     

Detection of autoreactive antibodies to serum IgG and IgA in amoebic liver abscess cases.

Assessment of autoreactive antibodies in response to healthy human serum IgA and IgG was performed by indirect haemagglutination assay on serum samples from 81 amoebic liver abscess cases for IgA and 70 for IgG. Appropriate controls were taken simultaneously. IgA, IgG were isolated and purified from a healthy human serum through Sephadex G-200 and protein A CL 4B sepharose chromatography. These immunoglobulins were used for the detection of its own antibodies in amoebic liver abscess cases. This revealed that 43.20% and 48.50% of the cases were positive for IgA and IgG respectively, where as only 19.35% and 28.30% of the controls were in positive category (IgA and IgG respectively). The mean titres with standard deviation of the autoreactive antibodies to serum IgA both in ALA cases and controls shows a highly significant difference between tests and controls (P less than 0.001). Similarly the mean titres with standard deviation both in ALA and controls for the serum IgG differed significantly (P less than 0.001). This suggests the presence of autoreactive antibodies against serum IgA and IgG in amoebic liver abscess cases.     

Bactericidal Immunity to Salmonella in Africans and Mechanisms Causing Its Failure in HIV Infection

Background

Nontyphoidal strains of Salmonella are a leading cause of death among HIV-infected Africans. Antibody-induced complement-mediated killing protects healthy Africans against Salmonella, but increased levels of anti-lipopolysaccharide (LPS) antibodies in some HIV-infected African adults block this killing. The objective was to understand how these high levels of anti-LPS antibodies interfere with the killing of Salmonella.

Methodology/Principal Findings

Sera and affinity-purified antibodies from African HIV-infected adults that failed to kill invasive S. Typhimurium {"type":"entrez-nucleotide","attrs":{"text":"D23580","term_id":"427513","term_text":"D23580"}}D23580 were compared to sera from HIV-uninfected and HIV-infected subjects with bactericidal activity. The failure of sera from certain HIV-infected subjects to kill Salmonella was found to be due to an inherent inhibitory effect of anti-LPS antibodies. This inhibition was concentration-dependent and strongly associated with IgA and IgG2 anti-LPS antibodies (p<0.0001 for both). IgG anti-LPS antibodies, from sera of HIV-infected individuals that inhibit killing at high concentration, induced killing when diluted. Conversely, IgG, from sera of HIV-uninfected adults that induce killing, inhibited killing when concentrated. IgM anti-LPS antibodies from all subjects also induced Salmonella killing. Finally, the inhibitory effect of high concentrations of anti-LPS antibodies is seen with IgM as well as IgG and IgA. No correlation was found between affinity or avidity, or complement deposition or consumption, and inhibition of killing.

Conclusion/Significance

IgG and IgM classes of anti-S. Typhimurium LPS antibodies from HIV-infected and HIV-uninfected individuals are bactericidal, while at very high concentrations, anti-LPS antibodies of all classes inhibit in vitro killing of Salmonella. This could be due to a variety of mechanisms relating to the poor ability of IgA and IgG2 to activate complement, and deposition of complement at sites where it cannot insert in the bacterial membrane. Vaccine trials are required to understand the significance of lack of in vitro killing by anti-LPS antibodies from a minority of HIV-infected individuals with impaired immune homeostasis.     

Serodiagnostics of chlamydial infections--significance of positivity in IgA and/or IgM antibody classes only

There was followed the development of serological findings in patients with proved positivity only in classes IgA and/or IgM of chlamydial antibodies (without IgG), which can be suspected of showing "false" positivity. 184 patients were repeatedly examined for chlamydial antibodies in their sera (interval between collections up to three months) using a genus specific rELISA. Sera were also tested for the evidence of IgM antibodies against capside antigen of Epstein-Barr virus (EBV) and against cytomegalovirus (CMV) using ELISA methods. In 75 (40.8%) of patients, IgA/IgM individual positivities were demonstrated even during the following sample test(s). In 28 (15.2%) of them, IgG evidence preceded and in 29 (15.7%) other patients positive seroconversion followed in this class. In 13 (7.1%) patients, IgG antibodies disappeared and subsequently reappeared. Only in 39 (21.2%) of these probands, antibodies IgA/IgM were not demonstrated at another examination. Active EBV, resp. CMV infection was proved in 24 (13.0%), resp. in 18 (9.8%) of patients. It is concluded that the evidence of positivities only in classes IgA and/or IgM mostly signal the onset of a primary infection (reinfection) or an active infection in patients with IgG production failures respectively. In these cases, a "false" positivity can be supposed to occur only in a minor extent.     

Preparation and immunogenicity of conjugate based on hydrazine-treated lipopolysaccharide antigen of Vibrio cholerae O139

A glycoconjugate construct was based on attachment of V. cholerae O139 hydrazine-treated lipopolysaccharide (LPS) to carboxylated bovine serum albumin (CBSA) via its amino group. The immunological properties of the glycoconjugate were tested using BALB/c mice, injected subcutaneously without any adjuvant three times at 2?weeks interval. The immunogenicity of the conjugate was estimated by enzyme-linked immunosorbent assay, testing of anti-LPS IgG, IgM, and IgA antibodies. The conjugate elicited a statistically significant increase of LPS-specific IgG levels in mice (p?<?0.001). The specific anti-LPS IgG and IgA response after the second booster dose was significantly higher compared with reference and unconjugated detoxified LPS response. Antibodies elicited by the dLPS–CBSA conjugate were vibriocidal.     

Specific immunoglobulin response in mice immunized with porins and challenged with Salmonella typhi

Specific antiporin antibody (IgG, IgM, and IgA) response was studied in control, infected, immunized-infected, and immunized mice. The activity of specific IgG immunoglobulins was found to be the highest in immunized and immunized-infected groups in which 87.5% protection had been observed by laboratory potency test in mice; the next-highest activities were those of IgM and IgA immunoglobulins. However, in the infected group the activity of specific IgM and IgG immunoglobulins was almost similar.     

Antibodies in the small intestine: mucosal synthesis and deposition of anti-glycosyl IgA, IgM, and IgG in the enterocyte brush border

Synthesis and deposition of immunoglobulins in the brush border was studied in organ-cultured pig small intestinal mucosal explants. Surprisingly, comparable amounts of IgM and IgA were synthesized during a 6-h pulse, and also newly made IgG was detected in media and explants, including the microvillar fraction. For IgA and IgM, this subcellular distribution is consistent with basolateral-to-apical transcytosis, mediated by the polymeric immunoglobulin receptor. IgG is a ligand for the Fc receptor FcRn, and beta2-microglobulin, the light chain of FcRn, coclustered in immunogold double labeling with IgG in subapical endosomes and in the basolateral membrane of enterocytes. In addition, beta2-microglobulin was copurified with IgG on protein G-Sepharose. Apical endocytosis of IgG, as judged by internalization of fluorescent protein G, was not detectable except in a few isolated cells. This suggests that IgG in the adult small intestine is transported across the enterocyte mainly in the basolateral to apical direction. Significant fractions of all immunoglobulins bound to lactoseagarose, indicating that "anti-glycosyl" antibodies, raised against commensal gut bacteria, are synthesized locally in the small intestine. By partial deposition in the brush border, these antibodies therefore may have a protective function by preventing lectin-like pathogens from gaining access to the brush border surface.     

Composition of immunoglobulins in brucellosis patients using DEAE-cellulose column chromatography.

The composition of immunoglobulins in patients with brucellosis was studied. The method of ion-exchange chromatography on DEAE-cellulose columns was used to define more precisely the physico-chemical character of cysteine-resistant antibodies. The study of IgM, IgA and IgG fractions obtained from the patients sera showed the IgG fraction to possess the greatest serological activity in the agglutination reaction, in the passive haemagglutination reaction and in Coomb's test. Specific antibodies in the remaining 2 fractions (IgA and IgM) were found only in single patients in low titres, mainly in Coomb's test (incomplete antibodies). The study of IgM, IgA and IgG serum fractions before and after cysteine treatment revealed cysteine-resistant antibodies to be usually IgG globulins. The presence of specific IgG antibodies in the sera of patients was found to correlate with active clinical manifestations of brucellosis.     

Bacterial flora from bronchoalveolar lavage and occurrence of class IgG and IgA antibodies to Chlamydia pneumoniae in patients with chronic obstructive pulmonary disease (COPD)

Bronchoalveolar lavage taken from 46 patients (ranging in age from 21 to 71 years, mean 50.6 +/- 13.9) was examined for aerobic and anaerobic bacterial flora. Sera taken from 39 of patients as well as sera taken from 25 healthy blood donors of similar age (P = 0.99) were examined to determine IgG and IgA antibodies to C. pneumoniae. Bacterial flora was routinely cultured and determined using ATB computer system (bioMérieux,). IgG and IgA antibodies were tested by the enzyme immunoassays (Labsystems, Finland, Helsinki). Sera containing anti -C. pneumoniae IgG antibodies with titers of 45 EIU or higher and IgA with titers of 12 EIU or higher were considered positive. 143 of aerobic and 74 of anaerobic bacterial strains were cultured. Streptococci group viridans, pneumococci, enteric bacilli, Haemophilus spp., Prevotella spp., Actinomyces spp., Bifidobacterium spp. and Veilonella spp. were most often cultured. 66.6% of patients had IgG or IgA antibodies, in contrast, to the control group in which 60.0% and 44.0% of examined blood donors had IgG and IgA antibodies respectively. COPD patients were more frequently positive for specific anti-C. pneumoniae antibodies than the healthy donors (p = 0.003). The difference in a seropositivity rate of specific IgA and IgG antibodies was significant (p = 0.00002 and p = 0.003 respectively). Bronchoalveolar lavage of patients suffering from COPD can be contaminated with high number of aerobic and anaerobic bacterial species, and immunological status of the patients indicated persistent infection caused by C. pneumoniae more often than in controls.     

Nasopharyngeal carcinoma patients from Norway show elevated Epstein-Barr virus IgA and IgG antibodies prior to diagnosis

BackgroundIgA antibodies against few Epstein-Barr virus (EBV) proteins are established serological markers for nasopharyngeal carcinoma (NPC). We recently validated a novel, comprehensive EBV marker panel and showed that IgA, but also IgG antibodies against multiple EBV proteins are highly sensitive and specific for EBV-positive NPC at diagnosis. However, data about these novel biomarkers as prospective markers for NPC are sparse.MethodsThis study included 30 incident NPC cases and 60 matched controls from the Norwegian Janus Serum Bank. For 21 NPCs, molecular EBV and human papillomavirus (HPV) status were assessed by EBER-ISH and HPV DNA/RNA testing by PCR, respectively. IgA and IgG serum antibodies against 17 EBV antigens were analyzed in prediagnostic sera of cases (median lead time 14 years) and controls using multiplex serology. Sensitivities were calculated using receiver operating characteristic analysis pre-specified to yield 90% specificity in the control group. From 10 cases, serial samples were available.ResultsQuantitative EBV antibody levels were significantly elevated among all cases (p < 0.05) for three IgA and six IgG antibodies. The highest sensitivities for defining 12 EBER-ISH-positive NPCs were observed for BGLF2 IgA (67%) and BGLF2 IgG (83%). Increased IgA and IgG antibody levels between the first and last draw before diagnosis were observed for EBER-ISH positive, but not for EBER-ISH negative NPCs. Among 21 molecularly analyzed NPCs, 4 EBER-ISH negative NPCs showed concomitant positivity to HPV type-specific DNA and RNA; 3 NPCs were HPV16 and 1 NPC was HPV18 positive.ConclusionBoth, EBV IgA and IgG antibody levels are significantly elevated many years before diagnosis of EBV-positive NPCs in Norway, an NPC low-incidence region. This study provides insights into one of the largest available prospective sample collections of NPCs in a non-endemic country.     

Ordering of antibodies, that react with cardiac muscle fiber and interstitial connective tissue antigens, in different immunoglobulin classes

Sera of patients suffering from rheumatic diseases and myocarditis were examined on the sections of human and bovine myocardial tissue by indirect immunofluorescence with the use of pure IgG antibodies or monospecific sera against IgG, IgA and IgM. It was shown that antibodies reacting with different myofibers and interstitial connective tissue of the heart belong to the main immunoglobulin classes (IgG, IgA and IgM). There was a significant predominance of IgG antibodies as shown by the frequency of their detection and by the titer height. The predominance of antibodies to certain classes of immunoglobulins did not correlate with a specific disease entity. The frequency of detecting antibodies to a certain immunoglobulin class was in good agreement with the time of the disease onset. Moreover, the frequency of positive reactions due to IgG, IgA, and IgM antibodies correlated with the level of the appropriate immunoglobulins in the test sera.     

The production of specific immunoenzyme conjugates to human immunoglobulins by the glutaraldehyde method]

The results of studies aimed at obtaining class-specific conjugates to human immunoglobulins to be used in the enzyme immunoassay (EIA) are presented. At the first stage of the studies purified IgA, IgM and IgG preparations were obtained. These preparations were used for obtaining immunologically active immunosorbents on the basis of bromocyanic Sepharose. Specific antibodies to human IgA, IgM and IgG were isolated from animal sera by the method of affinity chromatography. These antibodies were conjugated with peroxidase by the glutaraldehyde method. The specific activity of the conjugates were determined in EIA. The results thus obtained revealed that all preparations exhibited high specific activity and gave no cross reactions with immunoglobulins of other classes.     

IA-2 autoantibodies restricted to the IgG4 subclass are associated with protection from type 1 diabetes.

The tyrosine phosphatase-like protein IA-2 is a major target antigen for autoantibodies in the preclinical period of type 1 diabetes. In this study, we examined whether immunoglobulin isotypes and IgG subclass specific autoantibodies directed at IA-2 discriminate between children at risk of type 1 diabetes who progressed to diabetes vs. those who remained diabetes-free. IgG1-4, IgA and the IgE-specific IA-2 antibody (IA-2A) were measured by radioligand assays in 50 patients with type 1 diabetes and 41 ICA-positive siblings of patients with type 1 diabetes who were followed for diabetes development. Of 41 siblings, 32 were positive for IA-2A; of these, 59 % had IA-2 IgG1, 59 % IgG4, 16 % IgG3, 9 % IgG2, 16 % IgA and 13 % IgE antibodies. IA-2 IgG1 was the dominant isotype in prediabetic children (n = 14, 86 % positive) and patients with type 1 diabetes (98 % positive) whereas only 7 of 18 (39 %) non-progressors had antibodies of this isotype. In subjects that remained diabetes-free, a significantly higher frequency of IA-2 IgG4 in the absence of IgG1 was observed (50 %) compared to progressors (7 %) and patients with type 1 diabetes (0 %). Life-table analysis revealed that IA-2A restricted to IgG4 correlated with protection from type 1 diabetes (p < 0.003). In contrast, IA-2 IgG2, IgG3, IgE and IgA did not differ significantly between study groups. Our findings suggest that the measurement of IA-2 IgG1 and IgG4 subclass antibodies can serve as surrogate marker to discriminate between antibody positive subjects at high or low risk for rapid development of diabetes.     

IgA and IgG antigliadin,IgA anti-tissue transglutaminase and antiendomysial antibodies in patients with autoimmune thyroid diseases and their relationship to thyroidal replacement therapy

Celiac disease is a chronic illness of the small bowel caused by gliadin intolerance in genetically predisposed subjects. The aim of this study was to investigate serum levels of IgA and IgG antigliadin antibodies, IgA antiendomysial antibodies, and IgA anti-tissue transglutaminase antibodies in 169 patients with autoimmune thyroid diseases, i.e. chronic thyroiditis and Graves' disease. Antiendomysial antibodies were positive in 2 out of 169 persons (1.18%), IgA antigliadin antibodies in 15.98%, IgG antigliadin antibodies in 51.48%, and IgA anti-tissue transglutaminase in 14.79%. The prevalence of positivity was higher compared to the 1312 control blood donors described in our previous study (Vancíková et al. 2002) (p<0.05). Patients with chronic thyroiditis treated with a high replacement dosage of levothyroxin (125-200 microg daily) had higher serum levels of IgA antigliadin antibodies in comparison with patients treated with a lower dosage (50-100 microg daily) (medians: 13.00 vs. 19.69, p=0.033). We found a negative correlation of IgA anti-tissue transglutaminase antibodies and total calcium serum levels (r = -0.480, p=0.0236, n=22). We can conclude that in persons with autoimmune thyropathy there is a high prevalence of positive antigliadin, anti-tissue transglutaminase and antiendomysial antibodies. Latent celiac disease may lead to impaired resorption of therapeutically administered levothyroxine, calcium, or other substances.     

Development of monoclonal IgA and an apparent IgG in a patient with macroglobulinemia: sharing of individually specific antigenic determinants among IgM, IgA, and IgG.

Patient CM, who initially was diagnosed as having macroglobulinemia (IgM, kappa) was subsequently found to develop a monoclonal IgA(kappa) protein. Rabbit antisera directed against the patient's IgAm and IgM were rendered specific for individual antigenic (ind) determinants. The anti-IgAm and IgM ind sera reacted with both 131I labeled monoclonal proteins in a double antibody radioimmunoassay (RIA). In addition, both monoclonal immunoglobulins inhibited the reaction between labeled immunoglobulin and both ind antisera, and statistical analysis of the data suggested that the shared ind determinants were identical. The IgG fraction of patient CM's serum also contained a component which competed with both monoclonal IgA (CM) and IgM (CM) in the RIA specific for ind determinants. Analysis of serum samples taken over a 2-year period revealed that, in addition to IgM, both the IgA and IgG components possessing the shared ind determinant(s) were present in low concentrations in the earliest sample, although not detected by conventional techniques. The monoclonal IgA and the IgG component were found to increase in concentration over this time interval with a concomitant decrease in IgM. The regulation of immunoglobulin expression with respect to the proposed models of gene organization in antibody-producing cells was discussed.     

Monoclonal antibodies to Chlamydia psittaci: their isolation, characteristics and use]

A panel of 22 hybridomas producing monoclonal antibodies (McAb) to C. psittaci was obtained. 15 hybridomas produced IgG1 antibodies, 4 hybridomas produced IgM antibodies and 3 hybridomas produced IgG2b, IgG3 or IgA antibodies. IgG1 antibodies and 2 IgM antibodies did not bind complement in the complement fixation test. All McAb were reactive in the enzyme immunoassay and the indirect immunofluorescence test and did not precipitate specific antigens. Peroxidase conjugates on the basis of McAb effectively detected Chlamydia antigen, prepared from the crude suspension of chick embryo yolk sack infected with different strains of C. psittaci and C. trachomatis, in different modifications of EIA.     

Shifts in immunoglobulin (IgG,IgM and IgA) levels in the milk of southern elephant seals,at Potter Peninsula,King George Island,Antarctica

We quantified immunoglobulins (Ig) in mammary secretions of 12 female southern elephant seals ( Mirounga leonina) at King George Island, Antarctica, using single radial immunodiffusion on agarose plates. Seals were chemically immobilized for milk sample collection at four time points during the 3- to 4-week suckling period. All three major mammalian immunoglobulins (IgG, IgM, IgA) were detected in southern-elephant seal milk. Total immunoglobulin levels and the ratio of Ig subclasses varied throughout the suckling period. Total immunoglobulin levels were highest on the 1st day of lactation, when they represented over 57% of the mean total protein concentration of the milk, and declined steadily throughout lactation, representing approximately 40% of the mean total protein concentration at the end of the suckling period. IgG was the most abundant immunoglobulin class (85.93-93.78% of total milk immunoglobulins), followed by IgM (6.06-13.93%), and IgA (0.14-0.23%). There was no significant difference in IgA levels throughout the suckling period. IgG levels were significantly lower during the second stage (3-6 days post-parturition) than during the first, third or fourth stages (1, 13-15, and 19-25 days post-parturition, respectively). IgM levels were highest during the first stage of lactation; these values were significantly higher than levels measured during the second, third and fourth stages of lactation. Transfer of passive immunity from female to offspring in other mammalian species is correlated with the subclass of immunoglobulin secreted in the milk; species acquiring passive immunity in utero, via the placenta, secrete a preponderance of IgA, whereas species acquiring immunity post-partum, via lacteal secretions and gut resorption, secrete a preponderance of IgG. The Ig patterns and concentrations observed in our study of southern elephant seals are consistent with an important role of post-partum transmission of passive immunity during the pinniped lactation period.     

IgA antibodies to Chlamydia trachomatis and metabolic syndrome

Chlamydia pneumoniae may trigger atherogenesis. Chlamydia trachomatis (CT) can also induce endothelial activation. However, its role in metabolic syndrome (METS), a proatherogenic entity, has remained unexplored. In this study the frequencies of IgA and IgG anti-CT antibodies were evaluated by immunoenzymatic assay in METS patients and healthy controls. The survey included 238 individuals (148 with METS). The mean age was 59.7 years. IgA anti-CT antibodies were found significantly more frequently in METS patients (16.9%) than in controls (5.6%) (P= 0.015). The role of such IgA response in METS should be further investigated.