Modulation of neutrophil Fc and C3b receptors

The effect of the interaction between human neutrophils and aggregated IgG on the expression of the receptors for the Fc portion of IgG (FcR) and for the C3b (C3R) has been investigated. Incubation of neutrophils with the appropriate concentrations of aggregated IgG at 37°C caused the loss of both the FcR and the C3R. This loss (modulation) was energy dependent (i.e., did not take place in cells incubated in the cold) and irreversible in that neutrophils did not reexpress either of the two receptors even upon prolonged incubation in vitro. The mechanisms leading to the modulation of FcR and C3R were different. FcR modulation was independent of the activation of the respiratory burst, since it occurred also in neutrophils from chronic granulomatous disease patients and was not induced by treatment of normal neutrophils with drugs such as phorbol myristate acetate (PMA), known to activate the respiratory burst. The FcR modulation was rather related to the redistribution (“capping”) and endocytosis of the FcR induced by the interaction with aggregated IgG. This possibility was supported by the finding that FcR modulation was blocked by inhibitors of phagocytosis and by the observation that aggregated IgG, tagged with a fluorescent dye, were “capped” and subsequently endocytosed by metabo'lically active cells. Modulation of C3R was dependent upon the activation of the respiratory burst induced by the interaction of aggregated IgG with the neutrophils. This hypothesis was also supported by the finding that the modulation of C3R was induced by treatment of the cells with PMA and did not occur in chronic granulomatous disease neutrophils treated with aggregated IgG or PMA. Furthermore the modulation of C3R was inhibited by the addition of catalase, suggesting that such modulation was consequent to the damaging effect of the oxygen active by-products on the receptor structures. In addition to the C3R modulation described above, another type of C3R loss was observed. This occurred in chronic granulomatous disease (CGD) neutrophils following interaction with the appropriate antigen-antibodycomplement complexes. In these cells, phagocytocis of the complexes caused a concomitant modulation of the C3R that was possibly related to the redistribution and endocytosis of the C3R structures.     

Enzyme treatment of unfixed cell cultures as a means of determining different specificities of immunoglobulin-M in multiple sclerosis and measles

Treatment of measles virus-infected cells with phospholipase C or with proteases alters the fluorescent staining pattern subsequently produced by IgM from measles patients (measles-IgM) and by IgM from multiple sclerosis patients (MS-IgM). Receptors for measles-IgM appear to be more resistant to phospholipase C and less resistant to proteases than are these from MS-IgM. Specific attachment of both types of IgM is abolished by mild periodate treatment. The cell membrane becomes permeable to IgG and IgM when treated with phospholipases A, C or D or with lysolecithin. Such treatment and mild treatment with certain organic solvents produce aggregates which have an afrinity for IgM of undetermined specificity.     

Intravenous immunoglobulin-mediated immunosuppression and the development of an IVIG substitute

Immunoglobulins are glycoproteins produced by the cells of the immune system. Their primary function is to protect the body from pathogenic infection. Moreover, a concentrated polyclonal mixture of immunoglobulin G (IgG), the so-called intravenous IgG (IVIG), has been used to treat various chronic and systemic disorders of the immune system. Studies on the effects of IVIG in autoimmune disease models have revealed that IgG Fc fragments confer protection against various autoimmune diseases. The identification of this IgG Fc immunomodulatory component is important for the development of IVIG substitutes. The focus of this review is to introduce one of the Fc regulatory entities and to provide a summary of the current knowledge of the putative general mechanisms underlying IVIG activity in vivo on the basis of these Fc fragments. We also address the recent insights into several approaches for the development of IVIG substitutes.     

Some immunochemical properties of natural antiglobulin factors (homoreactants)

A naturally occurring antiglobulin factor against the Fab-fragment of homologous IgG, contained in the rabbit and human blood serum and γ-globulin preparations, was shown by gelfiltration on Sephadex G-200 to have a molecular weight of about 250,000 daltons. In man this factor does not pass through the placenta in normal pregnancy. Despite differences in the physicochemical and effector properties of 7S IgG and protein with homoreactant activity, the latter has the specific antigenic determinants of IgG. These observations suggest that a complex of IgG with another protein or nonprotein compound possesses homoreactant properties.     

Antibody-dependent cell-mediated cytotoxicity againstEscherichia coli O antigens

Antibodies againstEscherichia coli O antigen from rabbits immunized with formalin-killed bacteria were tested for cytotoxic capacity in an antibody-dependent cell-mediated cytotoxicity (ADCC) assay with human lymphocytes as effector cells and autologous papainized erythrocytes coated with O antigen as target cells. The cytotoxic titres were compared with the titres obtained with three methods of antibody quantitation. It was found that ADCC recorded antibodies with similar sensitivity as the enzyme-linked immunosorbent assay (ELISA) for IgG, but was much more sensitive than the ammonium sulphate precipitation (ASP) and indirect haemagglutination (IHA) usingβ-mercaptoethanol reduced sera. The ADCC titres were found to correlate very well with the titres obtained with ASP, ELISA and IHA for IgG but not for IgM, which is in accordance with a previous notion that ADCC is primarily mediated via IgG antibodies. ADCC should be considered as a possible immunopathologic mechanism in renal parenchymal damage in connection with urinary tract infections.     

Impact of socioeconomic risk factors on the seroprevalence of cytomegalovirus infections in a cohort of pregnant Polish women between 2010 and 2011

The purpose of this investigation was to perform an evaluation of the prevalence and socioeconomic risk factors for human cytomegalovirus (HCMV) infections in a cohort of Polish pregnant women between 2010 and 2011. HCMV-specific IgG and IgM antibody levels were assayed with enzyme-linked immunosorbent assay (ELISA) tests in serum samples collected from 1,250 pregnant women attending outpatient obstetric clinics and hospitalized at two hospitals in Lodz. The seroprevalence of anti-HCMV IgG and IgM antibodies was 62.4 and 2.2 %, respectively, and differed significantly between age-stratified groups (p?≤?0.05). The highest IgG prevalence was observed in women above 36 years of age (76.2 %) and IgM in adolescent women aged 16–20 years (6.0 %). Of the various socioeconomic factors, age above 36 years, basic and professional education, and offspring were significantly associated with HCMV IgG prevalence rates (PRs; 1.89, 1.80, and 1.56, respectively). Financial status, occupational risk related to contact with children, and transfusions were not related to the prevalence of IgG antibodies. The IgM prevalence was not associated with any of the analyzed risk factors. A slightly higher prevalence was observed in women who were transfused in the past, but the relationship was not significant. The current data have revealed a decrease in HCMV IgG seroprevalence in our region during recent years (62.4 vs. 76.7 %). Basic and professional education, as well as bringing up offspring, were determined as significant risk factors for HCMV infections in Polish pregnant women [risk ratio (RR) 1.20 and 1.17, respectively], suggesting that the primary and secondary prophylaxis of cytomegaly is necessary during pregnancy, even if screening is not mandatory.     

Subcellular fractions in rubella immunoassays

Rubella virus-infected cells were fractionated by differential and sucrose gradient centrifugations. Rubella virus antigens distributed into all fractions but particulate material in the 100, 000×g pellet was shown to be enriched about two-fold for rubella virus antigen. Similarly, sucrose gradient fractions for rough endoplasmic reticulum and smooth cellular membranes were enriched for rubella virus antigens. The 100, 000 ×g pellet and the isolated cellular membranes proved to be useful when different fractions were used in solid-phase immunoassays for rubella virus-specific IgG or IgM. These fractions were equal in quality of the semipurified rubella virus preparations in the IgG assays but inferior to those in the IgM assays. However, simultaneous use of 35/25 % sucrose fractions from infected and non-infected cells reveals non-specific binding of IgM to the antigens and renders the IgM tests more specific for rubella virus.     

Enzyme-linked immunosorbent assay for detection of solubleToxoplasma gondii antigen in acute-phase toxoplasmosis

Sixty-two sera from 51 patients with lymphadenopathy presumed to be due to acute-phase toxoplasmosis were tested for specific IgM class antibodies by both the immunofluorescence antibody toToxoplasma gondii in sera were first dissociated in 3M NaSCN. Antigen attached to the solid phase was detected with enzyme-coupled IgG antibody toToxoplasma antibody toToxoplasma gondii in sera were first dissociated in 3M NaSCN. Antigen attached to the solid phase was detected with enzyme-coupled IgG antibody toToxoplasma gondii. Neither hepatitis B surface antigen nor antigen ofMycoplasma pneumoniae, rubella, cytomegalovirus or herpes simplex virus interfered with this ELISA. Soluble antigen was detected in 13(30%) of 42 IgM-positive acute-phase toxoplasmosis patients and in only one of 20 sera cleared of IgM. None of an additional 44 IgM-negative patients with low IgG titres had a positive result in the antigen ELISA. Follow-up studies in four acute-phase toxoplasmosis patients showed that the soluble antigen cleared in all cases before the specific IgM antibodies. Simultaneous detection of IgM antibodies toToxoplasma gondii and soluble antigen would thus seem to indicate an early stage of the infection.     

Use of the enzyme-linked immunosorbent assay for the early diagnosis ofMycoplasma pneumoniae infection

IgM and IgG antibodies toMycoplasma pneumoniae were measured in 147 sera from four groups of patients by means of an indirect enzyme-linked immunosorbent assay (ELISA) and the results compared with those obtained by other methods. A good correlation was demonstrated between the complement fixation test and ELISA-IgM and to a lesser extent ELISA-IgG; for the metabolic inhibition test the reverse was the case. The indirect haemagglutination test appeared to detect mainly IgM antibodies. Low levels of IgM antibodies were dectected by ELISA in 60 sera of children not suffering from pneumonia. However, if only high titres (> 800) were regarded as indicative ofMycoplasma pneumoniae infection, a presumptive diagnosis could have been made in 42 of 73 single acute phase sera from patients. Comparable results were obtained with IHA. The diagnostic level of IgM antibodies was reached during the second week of the disease. It is concluded that examination of a single serum sample by either ELISA-IgM or IHA may assist in early diagnosis ofMycoplasma pneumoniae infection.     

Enzyme-linked immunosorbent assay for detection of immunoglobulin G and M antibodies to teichoic acid in intravascular staphylococcal disease

An enzyme-linked immunosorbent assay (ELISA) for detection of IgG and IgM antibodies to cell-wall teichoic acids ofStaphylococcus aureus and three defined coagulase-negative staphylococci was tested using serum samples from 11 cases of intravascular coagulasenegative staphylococcal infections, 13 cases ofStaphylococcus aureus endocarditis, and 24 patients with no evidence of infection. IgG antibody titers to all four teichoic acids in the 13 patients withStaphylococcus aureus endocarditis were significantly different from those in noninfected control patients (p<0.0001). In contrast, IgG antibody titers in serum from 11 cases of intravascular coagulase-negative Staphylococcal infection were not significantly different from those in control sera. There were no differences in IgM antibody titers of the three groups. Although the ELISA was sensitive in detectingStaphylococcus aureus endocarditis, it was not reliable in the detection of intravascular coagulasenegative Staphylococcal infections, even when tested with specific teichoic acid.     

Immunoglobulin levels in various clinical groups of human Brugian filariasis in Malaysia

Quantitation of serum immunoglobulin M, G, A, D and E levels was carried out in Malaysians withBrugia malayi infections. Results showed highly elevated levels of IgM and IgE as well as moderately elevated levels of IgG. These were most significant in patients with tropical pulmonary eosinophilia or elephantiasis. Serum IgE levels were extremely high in microfilaraemic patients (6,060±3.958 IU ml) probably due to a constant antigenic stimulation by dead and dying microfilariae.     

Cytotoxic and blocking antibodies in serum and spleen cell eluates of mice with Rauscher leukemia depending on its course

Functional antagonism of cytotoxic and blocking humoral antibodies belonging to the same class of IgG and directed against type-specific antigen of Rauscher virus was found. Progression of leukemia in C57BL/6 and BALB/c mice inoculated with Rauscher virus and Freund's complete adjuvant was shown to be coupled with the production of 7S immunoglobulin (IgG) antibodies blocking in vitro the cytotoxic effect of 19S antibodies against the group-specific surface antigen of mouse leukemias, and later blocking also 7S antibodies against type-specific antigen. Regression of leukemia in C57BL/6 mice is connected with the cessation of production of both types of blocking antibodies. Complete resistance of C57BL/6 mice to the leukemogenic action of Rauscher virus is brought about immunologically by the production of cytotoxic humoral antibodies against type-specific antigen in the total absence of production of blocking antibodies.     

CMV-encoded Fcγ receptors: modulators at the interface of innate and adaptive immunity

The constant region of IgG antibodies mediates antiviral activities upon engaging host Fcγ receptors (FcγRs) expressed by a variety of immune cells, such as antibody-dependent cellullar cytotoxcity (ADCC) executed by natural killer (NK)cells. Human cytomegalovirus (HCMV) is unique among viruses by encoding also an array of several Fcγ-binding glycoproteins with cell surface disposition and concomitant incorporation into the virion. Evidence is increasing that the virus-encoded Fcγ receptors differ in their Fcγ binding mode but effectively operate as adversaries of host FcγRs since they are able to prevent IgG-mediated triggering of activating host FcγRs, i.e., FcγRI, FcγRIIA, and FcγRIIIA. Here we discuss virus-encoded FcγRs as the first known HCMV inhibitors of IgG-mediated immunity which could account for the limited efficacy of HCMV hyperimmune globulin in clinical settings. A better understanding of their molecular mode of action opens up new perspectives for improving IgG therapies against HCMV disease.     

Rapid separation of immunoglobulin M by immunoaffinity chromatography for detection of specific antibodies to rubella andTreponema pallidum

A rapid and easy method for isolating IgM from serum specimens in order to detect specific antibodies againstTreponema pallidum and rubella virus by routine serologic procedures is described. Serum IgM was isolated by immunoaffinity chromatography using anti-human IgM antibodies covalently bound to controlled-pore glass beads in a microcolumn. The final concentration of the IgM in the samples tested amounted to at least 16 % (average 32 %) of the original concentration (corresponding to a serum dilution of 1∶<8). IgG contamination did not exceed 0.38 % of the original serum concentration. The capacity of the column was stable for at least 50 absorption/ elution cycles. The new technique enables rapid and reliable detection of specific IgM by the rubella hemagglutination inhibition andTreponema pallidum hemagglutination tests.     

Evaluation of the sensitivity of IgG and IgM ELISA in detecting Schistosoma mansoni infections in a low endemicity setting

Schistosomiasis is a major public health concern, with 200 million people infected worldwide. In Brazil, this disease has been reported in 19 states, and its prevalence in the city of Barra Mansa in Rio de Janeiro State is 1 %. The parasitological diagnostic methods currently available in these areas lack sensitivity; however, enzyme-linked immunosorbent assays (ELISAs) have been employed successfully for the diagnosis of schistosomiasis by using antibodies against antigens of Schistosoma mansoni adult worms and eggs, and for the detection of circulating antigens. The objective of this study was to determine systematically the prevalence of S. mansoni infection in the peripheral areas of Barra Mansa. A cross-sectional study was conducted from April to December 2011 by using probabilistic sampling that collected 610 fecal samples and 612 serum samples. ELISA-IgG with total extracts and ELISA-IgM with trichloroacetic acid-soluble fractions were employed to detect antibodies against S. mansoni and were compared with the Kato–Katz and Hoffman parasitological techniques. Among the individuals studied, anti-S. mansoni antibodies were detected in 11.16 % (n?=?71) by ELISA-IgG and in 20.75 % (n?=?132) by ELISA-IgM, while the parasitological techniques showed 0.82 % (n?=?5) positivity. The agreement between the two ELISA tests was 85.38 % (n?=?543), and 8.65 % (n?=?55) of the serum samples showed positive results in both tests. The higher positivity of the ELISA-IgM test corroborates the results of previous reports and indicates that the test may be a useful tool in epidemiological studies, particularly in areas of low endemicity for S. mansoni.     

Further study of fluorescent free-radical products in synovial fluid

Fluorescence (Ex 340–370 nm, Em 430–470 nm) in synovial fluid is associated with three fractions; IgG, albumin and an unidentified fraction. Albumin possesses the majority of the fluorescence (70–75%) and its response to pH change suggest a Schiff base structure. The fluorescence associated with the IgG fraction, however, is probably due to the free-radical oxidation of tryptophan residues. In a preliminary study significantly higher levels of fluorescence were observed in the IgG (p<0.001) and albumin (0.01>p>0.001) fractions isolated from synovial fluids of patients with ‘inflammatory’ as compared to ‘non-inflammatory’ conditions.     

Antibodies against different measles antigens and rubella in patients with multiple sclerosis and other neurological diseases

Antibodies against measles virus have been demonstrated in CSF of some patients with MS or a related disease as optic neuritis or myelopathy. This report describes antibody measurements in CSF of MS patients against different measles antigens and various other virus antigens compared with other nonmyelinating neurological diseases. CSF specimens were obtained from 63 MS patients and from 101 other neurological patients with diagnosis as meningo-encephalitis, Parkinsonism, GuillanBarré and disturbances in BBB. CF antibodies were measured against herpes simplex, zoster-varicella, mumps and RSSE, and HI antibodies against measles and rubella. Additional tests were measles HLI, RNP gel-precipitation, and quantitation of total proteins, IgG and albumin. No CF antibodies were found in either group. Positive rates of measles tests im MS patients were from 20 to 60%, and 6 to 9% in controls. Six control patients showed antibodies in measles HLI test. In a followup study a demyelinative process or disturbance in BBB was evident in four cases. The concentration of IgG was significantly higher among MS patients, but not amounts of albumin or total proteins, suggesting intrathecal synthesis of IgG. Rubella HI antibodies were found in 18% of MS patients compared with 2% in control group. Also rubella antibodies seemed to be correlated with a higher IgG level.     

Willignes to drive when drunk and personality: A twin study

In a laboratory study of psychomotor sensitivity to alcohol, twins were asked “Would you drive a car now?” at 1, 2, and 3 h after drinking a standard dose of ethanol (0.75 g/kg). Correlations among these binary items, the Eysenck personality scales, and age were investigated using PRELIS and LISREL. Willingness to drive and Extraversion correlate at all three times in both males and females. In males, willingness to drive also correlates with Psychoticism, and in females it correlates negatively with the Lie (or Social Desirability) scale. Most correlations between cotwins in willingness to drive were significant in both monozygotic (MZ) and dizygotic (DZ) male twins but correlations were lower in female twins. Factor and Markovian models were fitted. In males there seem to be both genetic and cultural influences on willingness to drive when drunk. About half the genetic variance seems to be the pleiotropic effects of genes influencing Extraversion. The correlationswith Psychoticism, on the other hand, seem to be largely environmental in origin. The small sample size and lack of proper significance tests mean that these results must be interpreted with caution.     

Comparison of an indirect fluorescent antibody test with Western blot for the detection of serum antibodies against Encephalitozoon cuniculi in cats

Current clinical research indicates that Encephalitozoon (E.) cuniculi infections in cats may be underdiagnosed, especially in animals with typical ocular signs (cataract/anterior uveitis). Although molecular detection of the pathogen in tissue appears promising, serology remains the major diagnostic tool in the living animal. While serological tests are established for the main host of E. cuniculi, the rabbit, the routine serological diagnosis for cats still needs validation. The aim of the study was to evaluate the consistency of indirect fluorescence antibody test (IFAT) and Western blot (WB) for the detection of IgG antibodies against E. cuniculi in the serum of 84 cats. In addition, PCR of liquefied lens material or intraocular fluid was performed in those of the cats with a suspected ocular E. cuniculi infection. Twenty-one cats with positive PCR results were considered as a positive reference group. Results obtained by IFAT and WB corresponded in 83/84 serum samples, indicating a very good correlation between both serological methods. Using WB as the standard reference, sensitivity and specificity for the detection of antibodies against E. cuniculi by the IFAT were 97.6 and 100 %, respectively. The positive and negative predictive values for the IFAT were 100 and 97.7 %, respectively. The accuracy (correct classified proportion) for the detection of IgG antibodies against E. cuniculi in cats was 98.8 %. The comparison of both serological methods with the PCR results also revealed a good agreement as 20 out of 21 PCR-positive samples were seropositive both in IFAT and WB. Both tests can be considered as equally reliable assays to detect IgG antibodies against E. cuniculi in cats. As the IFAT is quicker and easier to perform, it is recommended for routine use in the diagnosis of feline encephalitozoonosis.