Non-enzymatic glycosylation of proteins is one of the key mechanisms in the pathogenesis of diabetic complications. Glycation of IgG is of special interest due to its possible influence on the functionality of immunoglobulin and overall immuno-competence. The aim of this study was to clarify more details of in vitro glycation of IgG and to study the effect of this modification on its interation with anti-IgG. Purified human IgG was glycated in the presence of 50 and 100 mM glucose. Glycation was measured using spectrophotometric thiobarbituric acid method. To study the effect of glycation on interaction with anti IgG the Single Radial Immunodiffusion (SRID) was used and the diameters of precipitation rings of glycated IgG and non-glycated IgG were measured and compared. The results showed that IgG was glycated in presence of 50 and 100 mM glucose at 27°C and 37°C and the extent of glycation was dependent on glucose concentration and time of incubation. In higher concentration of glucose and longer period of incubation glycation was higher at 27° C (p<0.01). Similar results were obtained at 37°C.The results of SRID indicated that glycated IgG showed reduced interaction with anti-IgG. The diameters of precipitated rings for glycated IgG were significantly lower than those of non-glycated IgG (p<0.01). It can be concluded that modification that occurred in IgG structure due to glycation can be the reason of the reduction of its interaction with anti-IgG.

Background: Glycation of proteins is a non-enzymatic spontaneous process that occurs in diabetes mellitus and aging, altering the structure and function of proteins. IgG undergoes glycation leading to changes in its reactivity to antigen and fixation of complement. Objective: This study aimed at revealing the effect of glycation on the interaction of IgG with anti-IgG using electroimmunoassay. Methods: Purified human IgG was glycated with different concentrations of glucose and different periods of treatment. Glycation was measured using thiobarbituric acid reaction. Glycated and non-glycated IgG were subjected to electroimmunoassay, and the height of the precipitated rings were measured and compared. Results: The results showed that IgG was glycated in vitro and the level of glycation was dependent on the glucose concentration and duration of treatment with glucose. The height of glycated IgG peaks formed in the electroimmunoassay was significantly lower than those of non-glycated IgG (p < 0.01). Conclusion: The results indicated that in vitro glycation of IgG leads to structural changes altering its mobility in the electroimmunoassay. Moreover, it suggests that this alteration may cause the weakness of its interaction with anti-IgG. This phenomenon may play a role in the susceptibility of diabetic patients to infection.

Background: This study investigated the prevalence for hepatitis A virus (HAV), hepatitis E virus (HEV), herpes simplex virus type 2 (HSV2) and syphilis among homeless in the city of Tehran.Methods: In this cross-sectional study, 596 homeless were recruited in Tehran. A researcher-designed questionnaire was used to study demographic data. Using enzyme-linked immunoassay, and rapid plasma reagin (RPR) test, we evaluated the seroprevalence of HAV anti-body, HEV IgG, herpes, HSV2 IgG, and syphilis among sheltered homeless in Tehran. The associations between the participant’s characteristics and infections were evaluated using logistic regression and chi-square.Results: A total of 569 homeless, 78 women (13.7%) and 491 men (86.3%) were enrolled into the study from June to August 2012. Their age mean was 42 years and meantime of being homeless was 24 months. Seroprevalence of syphilis, HEV IgG, HSV2 IgG and HAV Ab was 0.55%, 24.37%, 16.48%, and 94.34%, respectively. History of drug abuse was reported in 77.70%; 46.01% of them were using a drug during the study and 26.87% of them had history of intravenous drug abuse. Among people who had intravenous drug abuse, 48.25% had history of syringe sharing.Conclusion: The prevalence of HAV, HEV and HSV2 were higher than the general population while low prevalence of syphilis was seen among homeless peoples who are at high risk of sexually transmitted infection (STD). Our findings highlighted that significant healthcare needs of sheltered homeless people in Tehran are unmet and much more attention needs to be paid for the health of homeless people.

Background and Objectives: A single reactive IgG anti-Dengue virus ELISA test in the absence of IgM antibodies or NS1antigen may denote current infection or past exposure to the virus. To determine whether IgG index value can be used toidentify true current dengue infection we conducted a prospective observational study.Materials and Methods: Suspected dengue patients (n=1745) were tested in their first specimen by MAC-ELISA, GAC-ELISA and NS1 antigen ELISA. Patients with MAC-ELISA and NS1Antigen non-reactive but GAC-ELISA reactiveresults (n=57) in their first test were followed up and repeated sampling was asked for IgG index values were calculatedaccording to the manufacturer’s instruction and classified as: low (2.2-2.5), medium (2.5-4.0) and high (>4.0).Results: 16 out of 57 patients (28.1%) had low IgG Index value whereas 26 cases (45.6%) were categorized as medium and15 (26.3%) were classified as patients with high IgG index. Nine patients with paired reactive serology or antigen positivestatus were categorised as serologically confirmed dengue fever, 11 patients as not dengue with categorical evidence of otherinfections while the rest 37 casas with clinical, radiological and laboratory parameters suggestive of dengue but no serologicalconfirmation as possible dengue. Among confirmed, possible and non-Dengue cases, 33.3, 32.4 and 0.0% had high Indexvalue in comparison with 22.2, 29.7 and 27.3% showing low Index values, respectively.Conclusion: Our results suggested a high IgG response in favour of true dengue infection than past exposure while no conclusionsshould drawn from a low or medium reactive GAC-ELISA results in the absence of IgM antibodies and NS1 Ag.

Background: This study was conducted to compare the efficacy of enzyme-linked immunosorbent assay (ELISA) for detecting anti-Helicobacter pylori (H. pylori) specific IgG antibodies in specimens of oral fluid and serum with bacteriological tests. Methods: Antral biopsy specimens, as well as serum and oral fluid samples were collected from 97 patients who underwent upper gastrointestinal endoscopy. The presence or absence of current H. pylori infection was determined by culture, histology and urease detection. Anti-H. pylori specific IgG was detected in serum and oral fluid, using an established lab-made, and a commercial ELISA kit. The obtained data were compared with results of bacteriological tests. Results: In all, 62 (64%) of 97 patients were positive for H. pylori by one or more of the gold standard tests (culture, histology and urease detection). Lab-made enzyme-linked immunoassay of oral fluid had a sensitivity and specificity of 92% and 83% respectively. A sensitivity and specificity of 87% and 83%, respectively, was obtained with the commercial kit. Lab-made enzyme-linked immunoassay of serum samples had a sensitivity and specificity of 90% and 88%, respectively. A sensitivity of 86% and specificity of 86% was obtained with the commercial kit. Conclusion: Detection of anti-H. pylori specific IgG in oral fluid by ELISA is comparable in sensitivity and specificity with serum based methods. Oral fluid based ELISA could provide a reliable, non-invasive method for the diagnosis of H. pylori infection. Saliva testing may have a role in epidemiological studies.