Immune Complexes In Plasma Research Articles

High glucose removes natural anti-α-galactoside and anti-β-glucoside antibody immune complexes adhering to surface O-glycoproteins of normal platelets and enhances platelet aggregation.

Human natural anti-α-galactoside (anti-Gal) and anti-β-glucoside (ABG) antibodies were previously reported to recognize the serine- and threonine-rich peptide sequences (STPS) of albumin-associated O-glycoproteins (AOP1 and AOP2) as surrogate antigens, forming anti-Gal/ABG-AOP1/AOP2-albumin triplet immune complexes in plasma. Since antibodies in these triplets still possessed unoccupied binding sites, the presence of triplets on human platelets that abound in surface O-glycoproteins was examined. Upon treatment with α-galactosides and β-glucosides, normal platelets freshly isolated from young healthy individuals released triplets identical with plasma triplets according to ELISA results. The resulting denuded platelets, unless pre-treated with fibrinogen or the O-glycan-binding lectin jacalin, recaptured these sugar-extracted triplets in the absence of antibody-specific sugars, suggesting that the triplet antibodies recognized the STPS of O-glycosylated receptors on platelets. Molecular weight of the dominant jacalin-binding subunit on triplet-free platelet membrane was 116 kDa, close to the ~120 kDa reported for the IIb subunit of the most abundant fibrinogen-binding platelet O-glycoprotein, GPIIb/IIIa. Denuded, but not native, platelets underwent slow spontaneous aggregation and rapid ADP-mediated GPIIb/IIIa-dependent aggregation according to spectrophotometric assay. Pre-treatment of denuded platelets with jacalin significantly reduced their ADP-mediated aggregation. Amyloid β (Aβ-42 monomer) was reported to bind triplet O-glycoproteins through their STPS but not to albumin or the antibodies. This peptide bound to the triplets on normal platelets and to surface membrane O-glycoproteins on denuded platelets, suggesting that the surface O-glycoproteins on the normal platelets were engaged and masked by the triplets. The ABG-specific sugar glucose denuded the platelets at concentrations typically reached in diabetic sera, since anti-Gal specific or ABG-specific sugar released the triplets of both the antibodies from the platelets. In conclusion, the present study offered rationale for the presence of anti-Gal/ABG-O-glycoprotein-albumin triplets on normal platelets, for the role of triplets in platelet physiology amidst circulating platelet-activating factors such as ADP, and for platelet vulnerability during diabetes.

Oral immunotherapy tolerizes mice to enzyme replacement therapy for Morquio A syndrome.

Immune response to therapeutic enzymes poses a detriment to patient safety and treatment outcome. Enzyme replacement therapy (ERT) is a standard therapeutic option for some types of mucopolysaccharidoses, including Morquio A syndrome caused by N-acetylgalactosamine-6-sulfate sulfatase (GALNS) deficiency. Current protocols tolerize patients using cytotoxic immunosuppressives, which can cause adverse effects. Here we show development of tolerance in Morquio A mice via oral delivery of peptide or GALNS for 10 days prior to ERT. Our results show that using an immunodominant peptide (I10) or the complete GALNS enzyme to orally induce tolerance to GALNS prior to ERT resulted in several improvements to ERT in mice: (a) decreased splenocyte proliferation after in vitro GALNS stimulation, (b) modulation of the cytokine secretion profile, (c) decrease in GALNS-specific IgG or IgE in plasma, (d) decreased GAG storage in liver, and (e) fewer circulating immune complexes in plasma. This model could be extrapolated to other lysosomal storage disorders in which immune response hinders ERT.

MMP-9/Gelatinase B Degrades Immune Complexes in Systemic Lupus Erythematosus.

Systemic Lupus Erythematosus (SLE) is a common and devastating autoimmune disease, characterized by a dysregulated adaptive immune response against intracellular antigens, which involves both autoreactive T and B cells. In SLE, mainly intracellular autoantigens generate autoantibodies and these assemble into immune complexes and activate the classical pathway of the complement system enhancing inflammation. Matrix metalloproteinase-9 (MMP-9) levels have been investigated in the serum of SLE patients and in control subjects. On the basis of specific studies, it has been suggested to treat SLE patients with MMP inhibitors. However, some of these inhibitors induce SLE. Analysis of LPR−/−MMP-9−/− double knockout mice suggested that MMP-9 plays a protective role in autoantigen clearance in SLE, but the effects of MMP-9 on immune complexes remained elusive. Therefore, we studied the role of MMP-9 in the clearance of autoantigens, autoantibodies and immune complexes and demonstrated that the lack of MMP-9 increased the levels of immune complexes in plasma and local complement activation in spleen and kidney in the LPR−/− mouse model of SLE. In addition, we showed that MMP-9 dissolved immune complexes from plasma of lupus-prone LPR−/−/MMP-9−/− mice and from blood samples of SLE patients. Surprisingly, autoantigens incorporated into immune complexes, but not immunoglobulin heavy or light chains, were cleaved by MMP-9. We discovered Apolipoprotein-B 100 as a new substrate of MMP-9 by analyzing the degradation of immune complexes from human plasma samples. These data are relevant to understand lupus immunopathology and side-effects observed with the use of known drugs. Moreover, we caution against the use of MMP inhibitors for the treatment of SLE.

IgA Complexes in Plasma and Synovial Fluid of Patients with Rheumatoid Arthritis Induce Neutrophil Extracellular Traps via FcαRI

Autoantibodies, including rheumatoid factor (RF), are an important characteristic of rheumatoid arthritis (RA). Interestingly, several studies reported a correlation between the presence of IgA autoantibodies and worse disease course. We demonstrated previously that triggering the IgA Fc receptor (FcαRI) on neutrophils results in neutrophil recruitment and the release of neutrophil extracellular traps (NETs). Because this can lead to tissue damage, we investigated whether IgA immune complexes in plasma and synovial fluid of RA patients activate neutrophils. RF isotypes were measured with ELISA, and immune complexes were precipitated using polyethylene glycol 6000. Isolated neutrophils were incubated with immune complexes, and activation and release of NETs were determined in the presence or absence of FcαRI-blocking Abs. Plasma and SF of RA patients contained IgM, IgG, and IgA RFs. Patient plasma IgA RF and IgM RF showed a strong correlation. No uptake of IgM and minimal endocytosis of IgG immune complexes by neutrophils was observed, in contrast to avid uptake of IgA complexes. Incubation of neutrophils with immune complexes resulted in the production of reactive oxygen species, as well as the release of NETs, lactoferrin, and chemotactic stimuli. Importantly, activation of neutrophils was reduced when FcαRI was blocked. Neutrophils were activated by IgA immune complexes, which suggests that neutrophils play a role in inducing joint damage in RA patients who have IgA autoantibody complexes, thereby increasing the severity of disease. Blocking FcαRI inhibited neutrophil activation and, as such, may represent an additional attractive novel therapeutic strategy for the treatment of RA.

Antigen DNA isolated from immune complexes in plasma of patients with systemic lupus erythematosus hybridizes with the Escherichia coli lac Z gene.

Antigen DNA was isolated from immune complexes in plasma of three patients with active systemic lupus erythematosus (SLE) using affinity column. The antigen DNA thus obtained was subjected to hybridization experiments in order to investigate its origin. Unexpectedly, plasmid pUC18 used as a probe was found to hybridize with the antigen DNA, pUC18 was then cleaved into three fragments with the restriction enzyme HaeII. A 445-bp fragment containing lac Z DNA hybridized with the antigen DNA. Finally, the lacZ DNA itself was found to hybridize with the antigen DNA. These data strongly suggest that the antigen DNA obtained from three patients is of bacterial origin.

Warm autoimmune hemolytic anemia is an IgM–IgG immune complex disease

Warm autoimmune hemolytic anemia (WAIHA) is characterized by polyclonal IgG autoantibodies binding to red blood cells (RBC). The characterization of the autoantigen in WAIHA has not yet led to definitive results, and the etiology of RBC autoantibodies remains unclear. An altered control of self-reactive IgG by autologous IgM has been proposed as the underlying mechanism of disease in WAIHA, suggesting that IgM–IgG immune complexes contribute to the pathophysiology of the disease. In the present study, we purified and characterized IgM from plasma of WAIHA patients and from healthy controls using FPLC-based protocols and optical biosensor technology, and investigated IgG present within the IgM fractions. We provide evidence that IgM–IgG immune complexes in plasma and associated with the RBC membrane are the characteristic feature of WAIHA, independent of the etiology of the disease. IgM–IgG immune complexes of WAIHA patients differ from IgM–IgG immune complexes of healthy individuals with regard to quantity and to structural composition. The data suggest that self-immunoglobulin is the original autoantigen underlying WAIHA. The molecular characterization of IgM–IgG immune complexes may define new targets for therapeutic intervention in WAIHA.

Antigenuria and antigenaemia in experimental murine paracoccidioidomycosis

In this study, Swiss mice were experimentally infected with Paracoccidoides brasiliensis (Pb18) and we investigated the levels of gp43 in urine and plasma, anti-gp43 and IgG-gp43 immune complexes in plasma. These levels were correlated with the histopathological findings. Blood and urine samples were collected from mice at 7, 28, 56 and 84 days after intravenous inoculation of 10(5) yeast cells, and analysed by ELISA. The results showed increased levels of soluble gp43 in the plasma in all periods, and anti-gp43 IgG and immune complexes after day 28. High gp43 levels were detected in the urine, except for day 28, coincident with the presence of compact granulomas in lungs. All the infected mice showed fungal cells in the lungs, with initial granulomatous lesions at day 7, dissemination of lesions to other organs at day 56, and granulomas lacking the surrounding mononuclear cells infiltration, especially at days 56 and 84. Our results suggest that gp43 diffuses passively into the urine, and the determination of gp43 levels in urine samples may be a non-invasive alternative method for diagnosis and follow up of PCM. Further studies are needed to determine if the cellular immune response correlate with decreased urine gp43 levels.

Human immunodeficiency virus (HIV) type 1 antibodies in perinatal HIV-1 infection: association with human HIV-1 transmission, infection, and disease progression. For the Women and Infants Transmission Study.

Anti -human immunodeficiency virus (HIV) type 1 antibodies in 242 pregnant women and 238 infants were measured at birth and at 1, 2, 4, and 6 months after birth, to estimate their association with perinatal transmission and infant disease progression. Maternal anti-p24 (P=.01) and anti-gp120 (P=.04) antibodies were inversely associated with vertical transmission rates, independent of maternal percentage of CD4 cells, hard drug use, duration of ruptured membranes, serum albumin levels, serum vitamin A levels, and quantitative HIV-1 peripheral mononuclear blood cell culture, but not with maternal plasma immune complex dissociated p24 or HIV-1 RNA copy number, both of which were highly correlated with antibodies. From ages 1-2 months, anti-gp120, -gp41, -p31, and -p66 decayed to a greater extent in infected than in uninfected infants. Infected infants produced anti-p24 antibody by age 2 months, anti-p17 by 4 months, and anti-p41 and anti-gp120 by 6 months. As early as birth, infants with rapid disease progression had lower levels of anti-p24 than did infants whose disease did not rapidly progress, but not independently of HIV-1 RNA levels.

CLINICAL UTILITY OF ASSAYS FOR IMMUNE COMPLEXES AND COMPLEMENT

Although a number of sensitive assays for the measurement of immune complexes in plasma or other body fluids have been described, a number of drawbacks limit the usefulness of these assays in clinical practice. These include lack of standardization, excessive interassay variation, and bias favoring the measurement of certain kinds of complexes and the exclusion of others. Such assays are useful for categorizing patients with suspected immune-mediated disease. Complement assays, by contrast, are standardized widely, reasonably reproducible, and quite sensitive to change during the course of a disease. Measurements of plasma complement levels repeatedly have been found to be reliable in predicting the course of a disease such as SLE but, as currently priced, are expensive and may not be cost-effective compared with other, more simple, assessments of disease activity.

Pathogenesis of early nephritis in lupus prone mice with a genetic accelerating (lpr) factor.

We investigated the relative roles of B cell activity, circulating immune complexes, complement concentration and kinetics of disappearance and uptake of immune complexes from the circulation in the pathogenesis of early nephritis of MRL/lpr mice. In comparison to data in control (C57BL/6J) mice, B cell activity was enhanced and the concentration of autoantibodies and endogenous immune complexes in plasma were increased, whereas complement (C3) concentration was not significantly different in MRL/lpr mice. The kinetics of disappearance of radiolabeled immune complexes from the circulation were similar in MRL/lpr and control mice, whereas uptake of radiolabeled immune complexes by the liver was decreased in MRL/lpr mice. Features of polyclonal B cell activation and impaired mononuclear phagocyte function are early events that may set the stage for progressive systemic involvement in MRL/lpr mice.

Production of antibodies specific for double stranded antigen DNA cloned from immune complexes in plasma of a SLE patient

The antigenicity of antigen DNA isolated from immune complexes in plasma of a SLE patient was examined. DDY mice were immunized with the cloned antigen DNA carrying a sequence homologous with a part of bacteriophage f1 (KS8 DNA) by the coupling method, and the antibody response was estimated by radioimmunoassay. Antibodies specific to double stranded DNA were elicited. Moreover, the antibodies showed preferential binding to KS8 DNA than other DNA derived from Escherichia coli . These results suggest that KS8 DNA has a significant antigenicity in mice.

Detection of Infectious Immune Complexes in Human Immunodeficiency Virus Type 1 (DIV-l) Infections: Correlation with Plasma Viremia and CD4 Cell Counts

The detection of infectious immune complexes in plasma after human immunodeficiency virus (HIV) infection may be useful as a surrogate marker of progression of disease and may help in understanding the pathogenesis of AIDS. Polyethylene glycol (PEG) precipitates of plasma were tested for the presence of HIV p24 antigen and infectious virus. Results were compared with data from cell and plasma cultures, plasma p24 antigen, CD4 cell counts, and stage of disease. PEG precipitation increased the detection rate of the p24 antigen assay from 38.3% to 58.7%. There was a significant correlation between precipitable p24 antigen and plasma viremia, changes in CD4 cell counts, and progression of disease. The sensitivity of the PEG-precipitable p24 antigen assay versus traditional p24 antigen testing was 59.0% and the specificity 91.7%. The assay was reproducible and may be a useful determinant of viral load, clinical progression, and antiretroviral efficacy.

Chromatographic and electrophoretic studies of circulating immune complexes in plasma

The protein nature of soluble immune complexes from fresh plasma was studied by combining several analytical biochemical techniques. Free immunoglobulins (Ig) G were separated from larger immune complexes by gel permeation chromatography. In a second step, immune complexes, free IgA and IgM were isolated by protein-A and protein-G affinity chromatography and analysed by two-dimensional gel electrophoresis. Sixteen plasma samples from healthy donors were analysed and evaluated visually. Their protein profiles on the gels turned out to be similar, showing only slight quantitative differences. In one case, additional proteins were detected. To prove the ability of the method, immune complexes were analysed from four plasma samples that showed macro creatine kinase type 1, a complex formation between creatine kinase BB and IgG. This methodology can be used for the examination of immune complexes of unknown protein composition in serum or plasma.

Demonstration of extrinsic DNA from immune complexes in plasma of a patient with systemic lupus erythematosus

Antigen DNA isolated from immune complexes present in plasma of three patients with active systemic lupus erythematosus using an affinity column was cloned and sequenced. One clone, designated pKS7, was found to have a region homologous with that of the E. coli met K gene, and another, designated pKS8, had a region homologous with a sequence including the replication origin of bacteriophage f1. Gel retardation assay revealed that pKS7 and pKS8 interacted with the patient's IgG fraction to form immune complexes, respectively. The affinity-purified antigen DNA was proved to be originated from bacteria or bacteriophage.

A reversible defect of platelet PDGF content in myeloproliferative disorders.

Platelet PDGF (platelet derived growth factor), platelet associated IgG and plasma levels of circulating immune complexes were measured in patients with chronic myeloproliferative disorders (primary myelofibrosis, primary proliferative polycythaemia and essential thrombocythaemia). Platelet PDGF was low in 11/12 patients, immune complexes were elevated in 11/16, and PlAIgG was elevated in all 14 patients in whom it was measured. There was no significant correlation between platelet PDGF and plasma levels of immune complexes (r = -0.5, P greater than 0.1). Treatment with busulphan and prednisolone for 2-3 months restored normal levels of platelet PDGF and suppressed plasma immune complex levels. Plasmapheresis lowered levels of immune complexes but had no effect on platelet PDGF. These results indicate that the low platelet PDGF levels in chronic myeloproliferative disorders represent a reversible defect which is not directly related to the presence of immune complexes.

A reversible defect of platelet PDGF content in myeloproliferative disorders

Platelet PDGF (platelet derived growth factor), platelet associated IgG and plasma levels of circulating immune complexes were measured in patients with chronic myeloproliferative disorders (primary myelofibrosis, primary proliferative polycythaemia and essential thrombocythaemia). Platelet PDGF was low in 11/12 patients, immune complexes were elevated in 11/16, and PlAIgG was elevated in all 14 patients in whom it was measured. There was no significant correlation between platelet PDGF and plasma levels of immune complexes (r= ‐0.5, P>0.1).Treatment with busulphan and prednisolone for 2–3 months restored normal levels of platelet PDGF and suppressed plasma immune complex levels. Plasmapheresis lowered levels of immune complexes but had no effect on platelet PDGF. These results indicate that the low platelet PDGF levels in chronic myloproliferative disorders represent a reversible defect which is not directly related to the presence of immune complexes.

Carcinoma-associated hemolytic-uremic syndrome: a complication of mitomycin C chemotherapy.

A thrombotic microangiopathy resembling the hemolytic uremic syndrome was diagnosed in 12 patients with adenocarcinoma, in whom the tumor was in complete or near-complete remission after treatment with mitomycin C-containing drug regimens. Microangiopathic hemolytic anemia, thrombocytopenia, and renal failure were initially present in all cases. All patients eventually developed pulmonary edema and systemic arterial hypertension, and three experienced neurologic complications. Blood transfusions exacerbated the syndrome in nine patients. High titers of platelet-aggregating plasma immune complexes were present in all six cases in which they were measured. The constituent antibody of each complex failed to react with mitomycin C antigen preparations, whereas in vitro reactivity to endodermally derived neoplasms was demonstrated. Plasmapheresis was associated with amelioration of the syndrome in only one patient. In patients receiving mitomycin C chemotherapy, the development of anemia and thrombocytopenia or azotemia may represent the initial manifestations of this newly defined thrombotic microangiopathy. A consistently effective form of management of this syndrome has not as yet been defined.

Antitumor activity with nontoxic doses of protein A.

This report confirms our previous observation that IV inoculation of purified protein A causes regression of rat mammary adenocarcinomas. In treated tumors, we have obtained histological evidence of changes indicating tumor cell destruction. Protein A treatment does not cause reduction in the body weight or organ weights of rats; nor does it cause any decrease in activity of the enzymes of the microsomal mixed function oxidase system in the liver. Protein A stimulates peripheral white cell counts in normal rats, but not in tumor-bearing rats. We found that protein A infusion reduced (P less than 0.0005) the level of circulating plasma immune complex concentration. A homing study with 125I-labeled protein A indicated that liver, spleen, and kidney tissues are the major sites of protein A accumulation. Therefore, protein A seemed to exert its antitumor effects without causing any generalized toxicity to the system. It is postulated that the action of protein A may be related to its ability to cause a drastic reduction in circulating plasma immune complex concentration, thus potentiating the immune reactivity of the host observed earlier.

免疫吸着材―血漿中の自己抗体、免疫複合体の吸着材について

免疫吸着材―血漿中の自己抗体、免疫複合体の吸着材について

Adsorbent for Rheumatoid Factor and Immune Complexes in Plasma

Adsorbent for Rheumatoid Factor and Immune Complexes in Plasma