Occurrence Of IgG Antibodies Research Articles

Occurrence of IgG antibodies against Toxoplasma gondii, Neospora caninum, and Leptospira spp. in goats and sheep from an indigenous village in Pernambuco, Brazil.

This study aimed to determine the occurrence of anti-Toxoplasma gondii, Neospora caninum, and Leptospira spp. antibodies in sheep and goats raised in villages of the Xukuru do Ororubá indigenous community, Pernambuco, Brazil. A total of 180 serum samples from sheep and 108 serum samples from goats of both sexes and different ages were analyzed. For antibody research, indirect immunofluorescence antibody test (IFAT) were used for the protozoa T. gondii and N. caninum, and microscopic agglutination test (MAT) for Leptospira spp., with a cutoff titer of 1:64, 1:50 and 1:100, respectively. The frequency of anti-T. gondii antibodies was 16.6% (30/180) for sheep and 11.1% (12/108) for goats. The frequency of anti-N. caninum antibodies was 10.55% (19/180) for sheep, and 20.37% (22/108) for goats, while for Leptospira spp., 2.2% (4/180) of sheep and 1.85% (2/108) of goats reacted positively. The results obtained in this study are unprecedented in indigenous communities in the country and serve as an alert for monitoring goats and sheep from the Xukuru do Ororubá indigenous village regarding the occurrence and productive impact of infections by T. gondii, N. caninum, and Leptospira spp., in addition to the occurrence of the zoonosis toxoplasmosis and leptospirosis in the indigenous community.

Inflammatory bowel disease is associated with higher seroprevalence rates of antibodies against SARS-CoV-2.

According to the current data, there has been no increase in the incidence of COVID‑19 in patients with inflammatory bowel disease (IBD). The available data are based on symptomatic cases and do not include the asymptomatic ones. To measure the exact infection rate, we initiated a study that aimed to assess the seroprevalence of anti-SARS‑CoV‑2 antibodies in IBD. A total of 864 individuals were enrolled in the study, including 432 patients with IBD (290 with Crohn disease and 142 with ulcerative colitis) and 432 controls without IBD (healthcare professionals) matched for age and sex. Serum samples were prospectively collected, and the presence of anti-SARS‑CoV‑2 immunoglobulin (Ig) G and IgM + IgA antibodies were measured using the enzyme‑linked immunoassay method (Vircell Microbiologists). A significantly higher percentage of positive results for anti-SARS‑CoV‑2 antibodies, both in the IgG and IgM + IgA class, was found in patients with IBD (4.6% and 6%, respectively, compared with 1.6% and 1.1%, respectively, in controls; both P values <0.05). No patient had symptomatic COVID‑19. There was no association among patients' age, sex, drugs used for IBD, or disease activity and the occurrence of IgG antibodies. Patients with IBD may be at higher risk of developing SARS‑CoV‑2 infection, defined as the presence of elevated levels of anti-SARS‑CoV‑2 IgG antibodies, but not of having a symptomatic and / or severe course of COVID‑19 compared with healthcare professionals without IBD.

Rectal methods of delivery of medical drugs with a protein nature in the therapies of tumor disease

The object of the study was rectal and/or vaginal suppositories (suppositories), intended for delivery to the patient&#39;s body of naturally occurring IgG antibodies of the type capable of inducing a specific antibody-complement-dependent lysis of any tumor cells (antibody phenomenon-complement-dependent lysis). Intravenous injection of protein drugs causes many negative side effects known as infusion reactions and serious consequences, such as serum sickness. This article shows the possibility

Endogenous antibody responses to mucin 1 in a large multiethnic cohort of patients with breast cancer and healthy controls: Role of immunoglobulin and Fcγ receptor genes

High levels of naturally occurring IgG antibodies to mucin 1 (MUC1), a membrane-bound glycoprotein that is overexpressed in patients with breast cancer, are associated with good prognosis. This suggests that endogenous anti-MUC1 antibodies have a protective effect and, through antibody-mediated host immunosurveillance mechanisms, might contribute to a cancer-free state. To test this possibility, we characterized a large number of multiethnic patients with breast cancer and matched controls for IgG antibodies to MUC1. We also aimed to determine whether the magnitude of anti-MUC1 antibody responsiveness was associated with particular immunoglobulin GM (γ marker), KM (κ marker), and Fcγ receptors (FcγR) genotypes. After adjusting for the confounding variables in a multivariate analysis, we found no significant difference in the levels of anti-MUC1 IgG antibodies between patients and cancer-free controls. However, in patients and controls, particular GM, KM, and FcγR genotypes—individually or epistatically—were significantly associated with the levels of anti-MUC1 IgG antibodies in a racially restricted manner. These findings, if confirmed in an independent investigation, could help identify individuals most likely to benefit from a MUC1-based therapeutic or prophylactic vaccine for MUC1-overexpressing malignancies.

Naturally Occurring IgG Antibodies for the Treatment of Malignant Pleural Mesothelioma

Naturally Occurring IgG Antibodies for the Treatment of Malignant Pleural Mesothelioma

Naturally Occurring IgG Antibodies Provide Innate Protection against Vibrio cholerae Bacteremia by Recognition of the Outer Membrane Protein U

Cholera epidemics are caused by Vibrio cholerae serogroups O1 and O139, whereas strains collectively known as non-O1/non-O139 V. cholerae are found in cases of extraintestinal infections and bacteremia. The mechanisms and factors influencing the occurrence of bacteremia and survival of V. cholerae in normal human serum have remained unclear. We found that naturally occurring IgG recognizing V. cholerae outer membrane protein U (OmpU) mediates a serum-killing effect in a complement C1q-dependent manner. Moreover, outer membrane vesicles (OMVs) containing OmpU caused enhanced survival of highly serum-sensitive classical V. cholerae in a dose-dependent manner. OMVs from wild-type and ompU mutant V. cholerae thereby provided a novel means to verify by extracellular transcomplementation the involvement of OmpU. Our data conclusively indicate that loss, or reduced expression, of OmpU imparts resistance to V. cholerae towards serum killing. We propose that the difference in OmpU protein levels is a plausible reason for differences in serum resistance and the ability to cause bacteremia observed among V. cholerae biotypes. Our findings provide a new perspective on how naturally occurring antibodies, perhaps induced by members of the microbiome, may play a role in the recognition of pathogens and the provocation of innate immune defense against bacteremia.

Detection of Toxoplasma gondii IgG antibodies in Nigerian Free-range Chickens using Indirect FluorescentAntibody Test (IFAT)

The detection of Toxoplasma gondii antibodies in free-range chickens (FRC) has become a method for monitoring soil contamination with T. gondii oocysts shed in cat faeces. Although several methods have been employed for T. gondii antibody detection in chicken sera, limited information is available on the use of indirect fluorescent antibody test (IFAT) for this purpose. This study was conducted to determine the occurrence of IgG antibodies to T. gondii in the sera of 241 FRC randomly obtained from 10 local government areas (LGAs) of Oyo state, southwestern Nigeria using IFAT. Antibodies specific for T. gondii were detected in 26 (10.8%) sera with titre of 1:25 in 26 samples, and 1:50 in 5 samples. Seropositive FRC were detected in all 10 LGAs of Oyo State. There was no significant association between T. gondii seroprevalence and age, gender or source of the FRC. The results of the present study show that the IFAT is valuable in detecting antibodies to T. gondii in FRC sera and that infection of these chickens with T. gondii is widespread in the study area. Adequate precautions should be taken during preparation of FRC from the study area for food, as they could serve as potential source of infection for humans.

Higher levels of antibodies to the tumour-associated antigen cyclin B1 in cancer-free individuals than in patients with breast cancer.

Cyclin B1 is a checkpoint protein that regulates cell division from G2 to the M phase. Studies in mice have shown that cyclin B1 vaccine-induced immunity significantly delayed or prevented the spontaneous cancer development later in life. We hypothesized that if these results showing a protective effect of anti-cyclin B1 antibodies could be extrapolated to the human condition, cancer-free individuals should have higher levels of endogenous antibodies than patients with cancers characterized by the over-expression of this tumour-associated antigen. To test this hypothesis, we characterized a large (1739 subjects) number of multi-ethnic patients with breast cancer (which over-expresses cyclin B1) and matched controls for anti-cyclin B1 immunoglobulin (Ig)G antibodies. Multivariate analyses, after adjusting for the covariates, showed that cancer-free individuals had significantly higher levels of naturally occurring IgG antibodies to cyclin B1 than patients with breast cancer (mean ± standard deviation: 148·0 ± 73·6 versus 126·1 ± 67·8 arbitrary units per ml; P < 0·0001). These findings may have important implications for cyclin B1-based immunotherapy against breast cancer and many other cyclin B1-over-expressing malignancies.

Serum or breast milk immunoglobulins mask the self‐reactivity of human natural IgG antibodies

B cells producing IgG antibodies specific to a variety of self- or foreign antigens are a normal constituent of the immune system of all healthy individuals. These naturally occurring IgG antibodies are found in the serum, external secretions, and pooled human immunoglobulin preparations. They bind with low affinity to antigens, which can also be targets for pathologic autoantibodies. An enhancement of naturally occurring IgG autoantibody activity was observed after treatment of human IgG molecules with protein-destabilizing agents. We have investigated the interactions of human immunoglobulins that were obtained from serum or from breast milk of healthy individuals or IVIg with human liver antigens. Proteins from an individual serum or milk were isolated by two methods, one of which included exposure to low pH and the other did not. Purified serum, mucosal IgM, IgA, and the fraction containing immunoglobulin G F(ab')2 fragments each inhibited the binding of a single donor or pooled IgG to human liver antigens. Our study presents findings regarding the role of the breast milk or serum antibodies in blocking the self-reactivity of IgG antibodies. It supports the suggestion that not IVIg only, but also the pooled human IgM and IgA might possess a potent beneficial immunomodulatory activity in autoimmune patients.

Distinct patterns of blood-stage parasite antigens detected by plasma IgG subclasses from individuals with different level of exposure to Plasmodium falciparum infections

BackgroundIn endemic regions naturally acquired immunity against Plasmodium falciparum develops as a function of age and exposure to parasite infections and is known to be mediated by IgG. The targets of protective antibodies remain to be fully defined. Several immunoepidemiological studies have indicated an association of cytophilic anti-parasite IgG with protection against malaria. It has been hypothesized that the initial antibody responses against parasite antigens upon first few Plasmodium falciparum infections is dominated by non-protective IgG2/IgG4 and IgM antibodies, which then gradually develop into protective response dominated by cytophilic IgG1 and IgG3 antibodies.MethodsNaturally occurring IgG antibodies against P. falciparum blood-stage antigens were analysed from plasma samples collected from four groups of individuals differing in age and level of exposure to P. falciparum infections. Western Blot profiling of blood-stage parasite antigens displaying reactivity with individual plasma samples in terms of their subclass specificities was conducted. Parasite antigens detected by IgG were grouped based on their apparent molecular sizes resolved by SDS-PAGE as high molecular weight (≥ 70 kDa) or low molecular weight (< 70 kDa). The number of discernable low molecular weight parasite antigens detected by different IgG subclass antibodies from each plasma sample was recorded. Using Wilcoxons rank sum test these reactivities were compared amongst groups of individuals with different levels of exposure to P. falciparum infections.ResultsIgG4 and IgM antibodies in plasma samples from all groups detected very few parasite antigens. IgG2 antibodies from all groups detected a common pattern of high molecular weight parasite antigens. Cytophilic IgG subclasses in plasma samples from individuals with higher levels of exposure to P. falciparum infections distinctly detected higher numbers of low molecular weight parasite antigens.ConclusionsIn the present study, there was no evidence for switching of antibody responses from non-cytophilic to cytophilic subclasses against blood-stage parasite antigens as a likely mechanism for induction of protective immunity against malaria.

Enhancing Antibody Fc Heterodimer Formation through Electrostatic Steering Effects: APPLICATIONS TO BISPECIFIC MOLECULES AND MONOVALENT IgG

Naturally occurring IgG antibodies are bivalent and monospecific. Bispecific antibodies having binding specificities for two different antigens can be produced using recombinant technologies and are projected to have broad clinical applications. However, co-expression of multiple light and heavy chains often leads to contaminants and pose purification challenges. In this work, we have modified the CH3 domain interface of the antibody Fc region with selected mutations so that the engineered Fc proteins preferentially form heterodimers. These novel mutations create altered charge polarity across the Fc dimer interface such that coexpression of electrostatically matched Fc chains support favorable attractive interactions thereby promoting desired Fc heterodimer formation, whereas unfavorable repulsive charge interactions suppress unwanted Fc homodimer formation. This new Fc heterodimer format was used to produce bispecific single chain antibody fusions and monovalent IgGs with minimal homodimer contaminants. The strategy proposed here demonstrates the feasibility of robust production of novel Fc-based heterodimeric molecules and hence broadens the scope of bispecific molecules for therapeutic applications.

Naturally occurring human IgG antibodies to intracellular and cytoskeletal components of human platelets

Immunoblotting of platelets that have been subjected to SDS-PAGE has revealed that sera from normal individuals contain IgG which binds to many platelet components. This binding was seen with autologous and heterologous platelets using serum of males and of nulliparous females who had not received blood transfusions. Although binding patterns of different sera were not identical, almost all sera caused IgG binding to platelet components of 87-90 kD, 140 kD (identified as vinculin) and 220-240 kD (tentatively identified as talin and actin-binding protein). Purified IgG showed the same binding pattern as whole serum and F(ab')2 fragments retained their ability to bind to many components. The titre of IgG binding in serum was 1:50-1600 while that of alloantibodies to the PlA1 antigen was 1:3200. IgG binding components were not secreted when platelets were stimulated and were rarely associated with isolated membranes, but were located either in platelet cytoplasm or cytoskeletons. IgG binding was decreased by absorbing sera with lysed platelets or isolated cytoskeletons, but only slightly with intact platelets. Microaffinity purification of IgG which formed a major band on immunoblots showed that it was antibody with specificity for vinculin or its degradation products. These findings suggest that normal sera contain naturally occurring IgG antibodies with specificity for intracellular platelet antigens and that in some cases their titre approaches that of antibodies of pathological significance.

Autoantibodies against the tumour-associated antigen GA733-2 in patients with colorectal carcinoma.

The tumour-associated antigen (TAA) GA733-2 is expressed as a non-secreted surface molecule on the majority of human colorectal carcinoma cells. The antigen has been used as a target for passive and active immunotherapy during the last decade. To determine the incidence of autoantibodies against this antigen, sera from 1068 patients with colorectal carcinoma were analysed for naturally occurring IgG antibodies against the baculovirus-produced GA733-2E protein. A total of 14.5% of the patients had IgG antibodies against the antigen. In 519 patients, sera were collected at the time of diagnosis and 15% of those patients had anti-GA733-2E IgG antibodies. There was a tendency to a higher frequency of patients with antibodies among those in the advanced Dukes stages: 11% in stage A and 32% in stage D respectively (P = 0.06). Antibodies could be detected for up to 10 years after the diagnosis. Patients with Crohn's disease or colitis ulcerosa (n = 20) did not elicit anti-GA733-2E antibodies. No healthy control donor (n = 45) had detectable antibodies against the antigen. The specificity of GA733-2E-reactive serum IgG was indicated by significant inhibition of mAb17-1A (originally used to define GA733-2) binding to the GA733-2E antigen. Sera of positive patients bound to the GA733-2-expressing human colorectal carcinoma cell line, SW948. No significant correlation was found between the presence of antibodies and survival in the present patient population. However, the high incidence of autoantibodies against this tumour antigen in colorectal carcinoma patients confirms its antigenicity in humans and supports the use of the GA733-2 antigen as a target for immunotherapy.

Mapping of B-Cell Epitopes Recognized by Antibodies to Histones in Subsets of Juvenile Chronic Arthritis

The sera of 138 patients with juvenile chronic arthritis (JCA) were tested in ELISA with the five individual histories, 34 histone peptides covering the full length of the four core histones, and two peptides corresponding to the N- and C-terminal domains of H1. The occurrence of IgG antibodies was examined regarding the different subsets of JCA (pauciarticular, polyarticular, and systemic onset) and regarding clinical features (chronic anterior uveitis, CAU) and other serological features (antinuclear antibodies, ANA). Seventy-two percent of the 138 sera reacted with at least 1 histone peptide. The peptides 204-218 of H1, 1-25 of H2B, and 111-130 of H3 were recognized by 22-28% of JCA sera, and 42% of JCA sera reacted with one or both peptides 1-25 of H2B and 111-130 of H3. The frequency of occurrence of anti-histone antibodies (AHA) regarding the type of histone fraction (H1, H2A, H2B, H3 and H4) or the regions of histones was not significantly different in the three subsets of JCA. No obvious association was found between IgG antibodies to histone peptides and uveitis. In the subset of pauciarticular JCA, 13/31 patients (41.9%) with CAU against 14/41 patients (34.1%) without CAU possessed IgG antibodies reacting with peptides of the C-terminal domain 83-135 of H3. This difference is not statistically significant. Finally, the presence of antibodies to histones and histone peptides cannot completely explain ANA reactivity found in patients' sera. Although antibodies to histone peptides occur frequently in the serum of children with JCA, the antibody profiles seem to be highly individual and do not correlate with disease subtype or activity. Identification of AHA present not only in the circulation but also in tissue deposits may provide better insight into the identification of pathogenic antibodies.

Characterization of the antibody response to a Haemophilus influenzae type b conjugate vaccine in children with recurrent lower respiratory tract infection.

Children with recurrent lower respiratory tract infection (RLRI) may respond poorly to polysaccharide antigens. To examine how such children respond to a polysaccharide coupled to a protein carrier, we immunized 15 children with RLRI aged 8-69 months and 15 carefully age-matched healthy controls once with a Haemophilus influenzae type b (Hib) conjugate vaccine. Total IgG subclasses, total antipolysaccharide Hib antibodies, and antipolysaccharide Hib antibodies of IgM, IgG, IgA, and IgG1-4 specificity were determined by ELISA. There were no significant differences between the two groups in any single total IgG subclass, but total IgG measured as the sum of all four subclasses was significantly lower in the children with RLRI than in the controls (P = 0.036). Before vaccination, the children with RLRI had significantly less IgG antipolysaccharide Hib antibody than the controls (P = 0.005), whereas 1 month later they had significantly more IgM antibody (P = 0.038). No other significant differences were found between the groups before or after immunization with respect to antipolysaccharide Hib antibodies. Since naturally occurring IgG antibodies are thought to be acquired partly as a consequence of antigenic stimulation on mucosal surfaces, we hypothesize that the low level of specific IgG found before immunization, as well as the low total IgG in the children with RLRI, may reflect an impaired ability to prime through mucosal surfaces. This is supported by our finding of an increased IgM response to Hib conjugate vaccine in these children, since this isotype predominates in the primary immune response, i.e., in the absence of immunologic memory.(ABSTRACT TRUNCATED AT 250 WORDS)

Naturally occurring ABO antibodies: long-term stable, individually distinct anti-A IgG spectrotypes.

Spectrotypes of naturally occurring IgG antibodies to histo-blood group substance A were analyzed by isoelectric focusing and a newly developed, non-radioactive affinity immunoblotting assay. Specificity was tested by preabsorption of sera on red blood cells and on four different types of blood group substance A. Clonotype-banding patterns of sera from 18 different blood donors were individually distinct, most of them showing an oligoclonal pattern with less than 15 visible bands. To analyze the influence of IgG subclass composition on spectrotype patterns, IgG subclasses were measured by ABO enzyme-linked immunosorbent assay (ELISA) and were shown to be mostly IgG1 and IgG2. Anti-A IgG1 spectrotypes could be detected with four sera and were also individually distinct. A series of six and seven serum samples, respectively from two donors was used to analyze the time-related changes of anti-A IgG spectrotypes. Banding pattern of both individuals remained stable during the whole observation period of 167 and 82 days, respectively, and no differences between follow-up samples could be detected. This long-term stability of individual anti-A IgG spectrotypes is backed by constant serum levels of anti-A IgG and -IgM antibodies during the observation period as measured by ABO ELISA.

Bacterial Evasion of the Antibody Response: Human IgG Antibodies Neutralize Soluble But Not Bacteria-Associated Group B Streptococcal C5a-ase

Most strains of group B streptococci (GBS) possess an enzyme that inactivates the human anaphylatoxin C5a by cleaving a heptapeptide from the carboxyl terminus of C5a. This enzyme, called GBS C5a-ase, has been purified to homogeneity and cleaves and inactivates C5a in physiologic buffer. The enzymatic activity of soluble C5a-ase is completely inhibited, however, in the presence of plasma or serum from normal human adults. The neutralization of soluble C5a-ase by plasma and serum results largely from naturally occurring IgG antibodies directed against C5a-ase. IgG does not neutralize C5a-ase present on intact encapsulated type III GBS but does neutralize the C5a-ase activity associated with a transposon-induced mutant strain of type III GBS that lacks capsule. The location of GBS C5a-ase on the surface of encapsulated type III GBS permits the C5a-ase to inactivate C5a while evading neutralization by IgG antibodies.

Natural occurring IgG and IgM antibodies to gram-negative bacteria and lipopolysaccharides in human sera

In sera of 28 non-infected elderly individuals, relationships between natural occurring antibody populations against O-antigen deficient lipopolysaccharides (J5LPS, ReLPS and Lipid A), a mixture of twelve O-antigen containing lipopolysaccharides (“mixed LPS”) and five different gram-negative bacterial strains, were assessed in a quantitative ELISA. Concomitant measurement of total IgG and IgM concentrations (in radial immunodiffusion assays—RIDA) allowed for the expression of IgG and IgM antibody concentrations per mg IgG.ml −1 and per mg IgM m −1 respectively. Statistically significant positive correlations were found between IgM antibody concentrations to all mentioned antigens for each possible combination ( r≥0·381; P<0·05). The strongest correlation was found between IgM concentrations to ReLPS and Lipid A ( r=0·852; P<0·001). IgG antibody concentrations to ReLPS correlated statistically significant with IgG antibody concentrations to Lipid A ( r=0·692; P<0·001), to J5LPS ( r=0·409; P<0·05) and to “mixed LPS” ( r=0·409; P<0·05). Beside the statistically significant correlations of IgG antibody concentrations to “mixed LPS” with ReLPS and with Lipid A ( r=0·528; P<0·001), IgG antibody concentrations to “mixed LPS” also correlated statistically significant with three gram-negative enterobacterial strains. These data indicate that the application of “mixed LPS” as a capture antigen for the selection of donor sera with a high IgG antibody concentration to this polyvalent antigen, eventually will yield a pooled serum which also contains relatively high IgG antibody concentrations to O-antigen deficient lipopolysaccharide preparations as well as enterobacterial strains.

Age related variations of serum concentrations of normally occurring IgG antibodies to Clostridium perfringens.

In studies using indirect immunofluorescence IgG antibodies to Clostridium perfringens were found in sera from healthy adults. Sera from 236 healthy children were examined. The normally occurring IgG antibodies to C perfringens were found to have an age related variation. Preliminary data suggest that they are not correlated to C perfringens alpha toxin. The antigen(s) against which the antibodies are directed is/are probably part of the cell wall, but its/their exact nature is not known.

Ectopic pregnancy and antibodies to Chlamydia trachomatis

Ectopic pregnancy is one of the most serious sequelae to acute salpingitis. Chlamydia trachomatis seems to be the most common etiologic agent of acute salpingitis. In the present study, we tested whether women with ectopic pregnancy had serologic evidence of a current or past chlamydial infection. Sixty-five percent of the women with ectopic pregnancy had IgG serum antibodies to C. trachomatis, and 21% of women pregnant in utero had such antibodies. Eleven percent of women with infertile husbands, 42% of women with cervicitis, and 69% of women with salpingitis had IgG serum antibodies to C. trachomatis. In women with ectopic pregnancy, there was a correlation between the occurrence of IgG antibodies and a history of salpingitis or gross evidence of a previous tubal inflammation. We conclude that previous chlamydial salpingitis may be a major etiologic factor leading to ectopic pregnancy.