Anti-idiotypes to Oxidized LDL Antibodies in Intravenous Immunoglobulin Preparations--Possible Immunomodulation of Atherosclerosis

Objective : The aim of this study was to examine whether intravenous immunoglobulin (IVIg) preparations contain anti-oxLDL and anti-anti-oxLDL antibodies. Background : Oxidized low-density lipoprotein (oxLDL) is one of the major players in atherogenesis. IVIg can reduce atherosclerosis in experimental animal models. Methods : Six commercial IVIg preparations were tested for the presence of anti-oxLDL antibodies by EIA. Inhibition studies were performed with the different IVIg preparations and IgGs purified from a pool of sera from patients with high anti-oxLDL antibody levels. Absorption assays were carried out to evaluate the presence of anti-idiotypes against anti-oxLDL antibodies in IVIg preparations. Results : IVIg preparations tested had various degrees of reactivity towards oxLDL. Absorption experiments suggested that the reactivity was specific because it could be effectively absorbed by oxLDL and not by an irrelevant antigen PPD. The reactivity was smaller than that observed with the IgG from the pool with high anti-oxLDL antibody levels. Inhibition studies with IVIg demonstrated 20-45% inhibition of anti-oxLDL binding to oxLDL, compared to 76% inhibition by the pool with high anti-oxLDL levels. To investigate the presence of anti-idiotypes against anti-oxLDL antibodies within IVIg, F(ab') 2 fragments of IVIg IgG were used to absorb IgG F(ab') 2 fragments from the pool of sera with high anti-oxLDL levels. The decreased binding to oxLDL of the absorbed supernatants shows that IgG F(ab') 2 fragments of the IVIg preparations had high inhibitory capacities ranging from 65 to 90%. Conclusions : IVIg preparations contain both anti-oxLDL and anti-anti-oxLDL activity. This finding may explain the immunomodulating effect of IVIg in atherosclerosis.     

Anti-idiotypes to oxidized LDL antibodies in intravenous immunoglobulin preparations--possible immunomodulation of atherosclerosis

OBJECTIVE: The aim of this study was to examine whether intravenous immunoglobulin (IVIg) preparations contain anti-oxLDL and anti-anti-oxLDL antibodies. BACKGROUND: Oxidized low-density lipoprotein (oxLDL) is one of the major players in atherogenesis. IVIg can reduce atherosclerosis in experimental animal models. METHODS: Six commercial IVIg preparations were tested for the presence of anti-oxLDL antibodies by EIA. Inhibition studies were performed with the different IVIg preparations and IgGs purified from a pool of sera from patients with high anti-oxLDL antibody levels. Absorption assays were carried out to evaluate the presence of anti-idiotypes against anti-oxLDL antibodies in IVIg preparations. RESULTS: IVIg preparations tested had various degrees of reactivity towards oxLDL. Absorption experiments suggested that the reactivity was specific because it could be effectively absorbed by oxLDL and not by an irrelevant antigen PPD. The reactivity was smaller than that observed with the IgG from the pool with high anti-oxLDL antibody levels. Inhibition studies with IVIg demonstrated 20-45% inhibition of anti-oxLDL binding to oxLDL, compared to 76% inhibition by the pool with high anti-oxLDL levels. To investigate the presence of anti-idiotypes against anti-oxLDL antibodies within IVIg, F(ab')2 fragments of IVIg IgG were used to absorb IgG F(ab')2 fragments from the pool of sera with high anti-oxLDL levels. The decreased binding to oxLDL of the absorbed supernatants shows that IgG F(ab')2 fragments of the IVIg preparations had high inhibitory capacities ranging from 65 to 90%. CONCLUSIONS: IVIg preparations contain both anti-oxLDL and anti-anti-oxLDL activity. This finding may explain the immunomodulating effect of IVIg in atherosclerosis.     

The IgE and IgG subclass antibody response in patients allergic to yellow jacket venom undergoing different regimens of venom immunotherapy

We developed a three-layer immunoradiometric assay for quantitation of IgG antibodies of all four subclasses to YJV. We studied the IgE and IgG subclass antibody response to YJV in 31 patients allergic to YJV who were undergoing three different kinds of venom immunotherapy. Group A received weekly single injections with alum-adsorbed venom, group B received weekly clustered injections with aqueous venom, and group C received fortnightly clustered injections with aqueous venom during the increasing dose phase of our study. All patients received alum-adsorbed venom during maintenance therapy. Results from the first 6 months of observation are reported. After 6 months of therapy the IgE antibody level rose significantly in group A, was unchanged in group B, and tended to fall in group C. The fall in IgE antibody level in group C correlated significantly to the pretreatment IgE antibody level. The IgG subclass antibody assays measured IgG antibodies of different subclasses in comparable units. No IgG2 or IgG3 antibodies to YJV were found. Before the start of immunotherapy, 23 patients had significant concentrations of IgG1 antibodies to YJV, and 14 had significant concentrations of IgG4 antibodies. In group A the IgG1 antibody level rose significantly after 6 months, and the IgG4 antibody level rose significantly after 3 months. In group B the IgG1 antibody level rose after 2 weeks and the IgG4 antibody level rose after 3 weeks. In group C the IgG1 antibody level rose after 2 weeks and the IgG4 antibody concentration rose after 8 weeks. When the maintenance dose was reached, the IgG1 antibody level in group C was significantly higher than that in group A. The possibility that IgG1 antibodies formed during venom immunotherapy take part in a feedback inhibition of the IgE antibody production is discussed.     

The autoreactivity of therapeutic intravenous immunoglobulin (IVIG) preparations depends on the fractionation methods used

Natural immunoglobulin G (IgG) autoantibodies are present in the plasma of healthy individuals and, as a result, in pooled therapeutic intravenous immunoglobulin (IVIg) preparations. The production processes of commercial IVIg preparations involve different fractionation and virus-inactivation steps that include in some cases treatments at extreme conditions. Different physical and chemical treatments are known to augment greatly the reactivity of natural autoantibodies to self-antigens. It is not clear to what extent the self-reactivity of IVIg preparations is due to the presence of natural IgG antibodies in the plasma pools used for fractionation, and to what extent it is due to the treatments that the IgG molecules have been subjected to during the fractionation process. We compared the binding of seven different commercial IVIg preparations to human liver antigens. All studied IVIg's could be clearly separated into two distinct groups: those that possess significant self-reactivity and those with low binding to self-antigens. Increased self-binding was seen in the preparations produced using a fractionation step at low pH. The treatment of IVIg at low pH resulted in increasing the inhibitory effect of the pooled IgG on PHA-induced proliferation of human peripheral blood mononuclear cells. IVIg's with high and low self-binding may have different immunomodulating activities when infused to autoimmune patients.     

Intravenous immunoglobulin: exploiting the potential of natural antibodies

Antibodies present in healthy conditions in the absence of deliberate immunization or infections are called natural antibodies. A significant proportion of natural antibody pool is believed to interact with self-antigens, and thus is called natural autoantibodies. Natural autoantibodies belong to IgG, IgM and IgA subclasses, and are encoded by V(D)J genes in germline configuration and bind to self molecules with varying affinities. In addition to serving in first line defense mechanism, natural antibodies participate in the homeostasis of the immune system. Intravenous immunoglobulin (IVIg) is a therapeutic preparation that contains substantial amount of natural antibodies exclusively of IgG subclass. In addition to its role in protection against pathogens in primary and secondary immunodeficiency patients, IVIg exerts a number of immunoregulatory functions through its interaction with innate and adaptive immune system and thereby imposing immune homeostasis.     

Human constant regions influence the antibody binding characteristics of mouse-human chimeric IgG subclasses

Although antibody affinity is primarily determined by immunoglobulin variable region structure human IgG antibodies of the four subclasses specific for the same antigen have been shown to differ in their affinity. To explore the influence of the immunoglobulin constant region on functional antibody affinity, a set of V region identical mouse–human chimeric IgG subclasses specific for TAG72 (tumour-associated glycoprotein) were studied. Biomolecular interaction analysis (BIA) was used to determine the binding kinetics of whole IgG subclasses and F(ab')₂ fragments. Despite identical V regions, binding kinetics differed for the four subclasses. The apparent dissociation rate constants of the intact immunoglobulins ranked IgG4 < IgG3 < IgG2 < IgG1. In contrast, analysis of the binding characteriztics of the F(ab')₂ fragments derived from IgG1, IgG2 and IgG4 revealed identical binding kinetics. The structure of the constant regions of the humanized IgG subclass antibodies clearly influenced functional antibody affinity, as has been described for the murine IgG subclasses. The exact mechanism for this phenomenon remains obscure but such differences should be taken into account when designing or choosing antibodies for therapeutic use.     

Alteration of the immunoglobulin G subclass responses in mice to lipopolysaccharide: effects of nonbacterial proteins and bacterial membrane phospholipids or outer membrane proteins of Proteus mirabilis

The immunoglobulin M (IgM) and the IgG1, IgG2ab, and IgG3 subclasses of plaque-forming cells (PFC) specific for lipopolysaccharide (LPS) were measured after immunization of mice with LPS alone and compared with the responses to LPS in combination with nonbacterial proteins and with bacterial membrane phospholipid vesicles or two major outer membrane proteins from Proteus mirabilis. The relative numbers of IgG PFC belonging to the IgG1, IgG2, or IgG3 subclasses induced by immunization with LPS alone depended upon the type of LPS administered. Phospholipids and the proteins effected characteristic alterations in not only the strength but also the subclass of the IgG responses to LPS. The results suggest that the hydrophobic-hydrophilic nature or state of aggregation of the preparations plays a role in the induction of IgG1 and IgG2 subclasses of PFC specific for LPS. Complex formation with LPS and adjuvant was apparently necessary to obtain these effects.     

Suppression of allo‐human leucocyte antigen (HLA) antibodies secreted by B memory cells in vitro: intravenous immunoglobulin (IVIg) versus a monoclonal anti‐HLA‐E IgG that mimics HLA‐I reactivities of IVIg

B memory cells remain in circulation and secrete alloantibodies without antigen exposure > 20 years after alloimmunization postpartum or by transplantation. These long‐lived B cells are resistant to cytostatic drugs. Therapeutically, intravenous immunoglobulin (IVIg) is administered to reduce allo‐human leucocyte antigen (HLA) antibodies pre‐ and post‐transplantation, but the mechanism of reduction remains unclear. Recently, we reported that IVIg reacts with several HLA‐I alleles and the HLA reactivity of IVIg is lost after its HLA‐E reactivity is adsorbed out. Therefore, we have generated an anti‐HLA‐E monoclonal antibody that mimics the HLA‐reactivity of IVIg to investigate whether this antibody suppresses IgG secretion, as does IVIg. B cells were purified from the blood of a woman in whose blood the B memory cells remained without antigen exposure > 20 years after postpartum alloimmunization. The B cells were stimulated with cytokines using a well‐defined culture system. The anti‐HLA‐E monoclonal antibody (mAb) significantly suppressed the allo‐HLA class‐II IgG produced by the B cells, and that this suppression was far superior to that by IVIg. These findings were confirmed with HLA‐I antibody secreted by the immortalized B cell line, developed from the blood of another alloimmunized woman. The binding affinity of the anti‐HLA‐E mAb for peptide sequences shared (i.e. shared epitopes) between HLA‐E and other β2‐microglobulin‐free HLA heavy chains (open conformers) on the cell surface of B cells may act as a ligand and signal suppression of IgG production of activated B memory cells. We propose that anti‐HLA‐E monoclonal antibody may also be useful to suppress allo‐HLA IgG production in vivo.     

Human antibody responses to bacteriophage phi X 174: sequential induction of IgM and IgG subclass antibody

We studied the appearance of antigen-specific immunoglobulin classes and IgG subclasses in normal adult human subjects in response to primary, secondary, and tertiary immunization with the T-cell-dependent neo-antigen bacteriophage phi X 174. To complete the study we developed a sensitive, specific, and reproducible ELISA assay which was closely comparable to the widely used neutralization assay for total antibody (r = +0.97) and for IgG antibody (r = +0.93), and reasonably comparable for IgM antibody (r = +0.76). We confirmed that the initial response to primary immunization was predominantly, but not exclusively, IgM antibody. The secondary and tertiary responses demonstrated memory, amplification, and switch from IgM to IgG antibody. There was an orderly appearance of phage-specific IgG subclasses. IgG3 and IgG1 antibodies appeared 2 to 6 weeks after primary immunization. In all subjects there was a marked increase in IgG1 and IgG3 antibody after secondary immunization, and IgG2 antibody followed closely; IgG4 antibody appeared in some subjects. IgM antibody persisted in significant amounts (approx 50%) throughout the secondary response period. Following tertiary immunization, IgG1, IgG2, and IgG3 antibody consistently increased, and IgG4 antibody appeared in all subjects; IgG1 antibody predominated. Low levels of IgM antibody (approx 1% of total) persisted during the tertiary response. The persisting antibody on long-term follow-up (median 4 years after immunization) was virtually all (greater than 90%) IgG1.     

Opsonophagocytic and Bactericidal Activity Mediated by Purified IgG Subclass Antibodies After Vaccination with the Norwegian Group B Meningococcal Vaccine

To study how the different immunoglobulin (Ig)G subclass antibodies may confer protection against systemic meningococcal disease, we isolated IgG1, IgG2 and IgG3 antibodies from plasma from vaccinees immunized with the Norwegian meningococcal outer membrane vesicle vaccine. Four IgG1, one IgG2 and four IgG3 preparations were purified. The IgG2 and IgG3 subclass preparations were free from contaminating subclasses, whereas the IgG1 preparations contained from 0 to 14% of IgG2 and/or IgG3. Immunoblotting against whole-cell meningococcal antigens showed broad specificities of the various preparations, both within and between subclasses. These subclass preparations were tested for opsonophagocytic and bactericidal activity. As targets we used two different variants of the meningococcal vaccine strain, with low (44/76-SL) and high (44/76-1) expression of the outer membrane protein Opc. Using polymorphonuclear leucocytes as effector cells in the presence of human complement, all three IgG subclass preparations revealed high, and similar, opsonophagocytic activities against 44/76-SL, whereas against 44/76-1 the IgG2 preparation showed a reduced activity and most IgG3 preparations were slightly more active than the IgG1 preparations. Regarding bactericidal activity, all the three subclasses were highly active against 44/76-SL. Against 44/76-1 the bactericidal activities were somewhat more varied: all IgG1 and three IgG3 preparations exhibited higher activities than against 44/76-SL. Due to the low concentration in the IgG2 preparations, only a weak activity was seen against 44/76-1. One IgG3 preparation that was highly opsonophagocytic revealed no bactericidal activity against either of the two bacterial variants examined. In conclusion, we have shown that the IgG subclass effector functions differ from person to person, but that antibodies of IgG1, IgG2 and IgG3 subclasses, judged by their behaviour in the functional tests, may all contribute to protection against meningococcal disease.     

Salmonella porins induce a sustained, lifelong specific bactericidal antibody memory response

We examined the ability of porins from Salmonella enterica serovar typhi to induce a long-term antibody response in BALB/c mice. These porins triggered a strong lifelong production of immunoglobulin G (IgG) antibody in the absence of exogenous adjuvant. Analysis of the IgG subclasses produced during this antibody response revealed the presence of the subclasses IgG2b, IgG1, IgG2a and weak IgG3. Despite the high homology of porins, the long-lasting anti-S. typhi porin sera did not cross-react with S. typhimurium. Notably, the antiporin sera showed a sustained lifelong bactericidal-binding activity to the wild-type S. typhi strain, whereas porin-specific antibody titres measured by enzyme-linked immunosorbent assay (ELISA) decreased with time. Because our porin preparations contained the outer membrane proteins C and F (OmpC and OmpF), we evaluated the individual contribution of each porin to the long-lasting antibody response. OmpC and OmpF induced long-lasting antibody titres, measured by ELISA, which were sustained for 300 days. In contrast, although OmpC induced sustained high bactericidal antibody titres for 300 days, postimmunization, the bactericidal antibody titre induced by OmpF was not detected at day 180. These results indicate that OmpC is the main protein responsible for the antibody-mediated memory bactericidal response induced by porins. Taken together, our results show that porins are strong immunogens that confer lifelong specific bactericidal antibody responses in the absence of added adjuvant.     

The nature of the autoantibody response to thyroglobulin in murine strains with high or low susceptibility to the experimental induction of autoimmune thyroiditis.

A sensitive three-layer solid phase immunoradiometric assay for estimating thyroglobulin antibodies in different mouse immunoglobulin subclasses was established and applied to study the subclass distribution of these antibodies in strains of mice differing in their susceptibility to the development of experimental autoimmune thyroiditis. Low response could not be ascribed to failure to produce a particular subclass. However, the absolute antibody levels in susceptible strains tended to be much higher, particularly in the IgG1, IgG2a and IgG2b classes 2 weeks after immunization. These differences in IgG1 and IgG2a persisted for a further 5 weeks but were less marked in the other subclasses. It would appear that antibody levels may be important in pathogenesis but since mice with high titres of thyroglobulin antibodies do not invariably develop thyroiditis, it is likely that further factors may be involved.     

Lipopolysaccharide- and cholera toxin-specific subclass distribution of B-cell responses in cholera.

The immunoglobulin subclass responses to homologous lipopolysaccharide (LPS) and to cholera toxin (CT) in adult patients infected with Vibrio cholerae O1 and V. cholerae O139 were studied. LPS-specific antibody-secreting cells (ASC) of both the immunoglobulin A1 (IgA1) and IgA2 subclasses were seen, with the IgA1 ASC response predominating in both V. cholerae O1- and O139-infected patients. For antibodies in plasma, by day 11 after onset of disease, all V. cholerae O1- infected patients responded to homologous LPS with the IgA1 subclass (P = 0.001), whereas fewer (68%) responded with the IgA2 subclass (P = 0.007). About 89% of V. cholerae O139-infected patients responded with the IgA1 subclass (P = 0.003), and only 21% responded with the IgA2 subclass (not significant [NS]). Both groups of cholera patients showed significant increases in LPS-specific IgG1, IgG2, and IgG3 antibodies in plasma. In feces, the response to homologous LPS occurred in both groups of patients with the IgA1 and IgA2 subclasses, with 55 to 67% of patients showing a positive response. V. cholerae O1- and O139-infected patients showed CT-specific ASC responses of the different IgG and IgA subclasses in the circulation, and the pattern followed the order IgG1 > IgA1 > IgG2 > IgA2, with low levels of IgG3 and IgG4 ASC. Plasma anti-CT antibody responses in all subclasses were seen by day 11 after onset of disease. Although there were no increases in CT-specific ASC of the IgG3 (NS) and IgG4 (NS) subtypes, there were significant increases of these two subclasses in plasma (P 相似文献   

A non-immune interaction between the light chain of human immunoglobulin and a surface component of a Peptococcus magnus strain

The immunoglobulin-binding capacity of a Peptococcus magnus strain was studied in a sensitive binding assay using purified human immunoglobulin preparations. The P. magnus strain 312 was capable of binding 48% of polyclonal IgG. Twenty-four of 40 purified myeloma proteins (60%) representing immunoglobulin classes A, G and M showed definite reactivity with an uptake level ranging from 45 to 90%. The remaining 16 monoclonal proteins were non-reactive, binding less than 15%. One myeloma protein with antistaphylolysin and two with antistreptolysin O specificity, i.e. monoclonal proteins with defined antigen specificity, were highly reactive. Binding capacity was observed in all four IgG subclasses and in Ig classes A and M. Twenty-three of 27 myeloma proteins of kappa type were reactive but only one of 13 myeloma proteins of lambda type interacted with the P. magnus strain. Isotope-labelled Fab gamma, F(ab')2 gamma and F(ab')2 alpha fragments were effectively bound by the strain. IgG Fc fragments were completely non-reactive. Isolated light immunoglobulin chains inhibited in a dose-dependent way the uptake of intact IgG to bacteria. Purified heavy chains were non-inhibitory. Isotope-labelled antistaphylolysin IgG F(ab')2 fragments preincubated with staphylolysin were as reactive as free antibody fragments, suggesting that the bacterial binding structure is located outside the antibody-combining site. The immunoglobulin reactivity of P. magnus was not affected by heating the bacteria to 80 degrees C for 5 min nor by treatment with trypsin or sodium metaperiodate. Digestion of 2 X 10(9) organisms with 100 micrograms of pepsin and papain reduced the binding by 58 and 90%, respectively. These data indicate that the binding of immunoglobulin to P. magnus is a non-immune reactivity mediated by a heat-stable surface protein interacting with specific sites on the light chain of the immunoglobulin molecule.     

Soluble CD4 antigen reactivity in intravenous immunoglobulin preparations: is it specific?

Soluble CD4 antigen (sCD4) was measured in seven commercially available intravenous immunoglobulin preparations (IVIg) by means of a double determinant immunoassay (DDIA), whereby two MoAbs recognizing two distinct and spatially distant epitopes on CD4 were used to capture and detect the antigen, respectively. Preincubation of six out of seven IVIg, which were found to be apparently positive for sCD4, with mouse- and bovine-derived serum or purified immunoglobulins completely neutralized DDIA reactivity for sCD4. The inhibition was specific since it was not or only partially observed when IVIg were mixed with whole serum or purified IgG from rabbit. Extensive absorption of six IVIg on insolubilized mouse IgG (mIgG) resulted in a complete loss of reactivity. Eluted human anti-mouse antibodies (HAMA) from any of the IVIg displayed a dose-dependent binding in a DDIA, though its extent varied from one preparation to another. Western blot analysis showed that HAMA from all IVIg contained no component with a molecular weight identical with or close to that of recombinant CD4. Purified mIgG markedly influenced the sCD4 reactivity of two IVIg (Sandoglobulin and Globuman I.V.) when sCD4 was measured with a purchased 'CD4-specific Test Kit', thus suggesting that HAMA can exceed the absorbing capacity of the sample diluent. Taken as a whole, these data indicate that sCD4-based DDIA signal is mostly, if not completely, generated by the presence of human immunoglobulin with anti-mouse immunoglobulin reactivity, thus casting doubts on the actual occurrence of sCD4 in IVIg.     

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.     

Placental transfer of IgG subclass-specific antibodies to varicella-zoster virus

Commercially available mouse monoclonal antibodies to human IgG subclasses (IgG 1 to IgG 4) were used in an enzyme-linked immunosorbent assay to examine the placental transfer of IgG subclass-specific antibodies to varicella-zoster virus (VZV). All 46 mothers had total IgG antibody to VZV, and an equal level of antibody was found in the cord blood. All of the mothers had high antibody activities to VZV in IgG 1 and IgG 4 subclasses. The majority of the mothers were negative for IgG 2 and IgG 3 VZV antibodies, and the level of antibody found to be positive was very low. The IgG 1 antibody activity in the cord blood was almost equal to that of the maternal, and significantly higher level of IgG 4 antibody was found in the cord than maternal blood.     

Down-Regulation of Lymphokine Synthesis by Intravenous Gammaglobulin is Dependent Upon Accessory Cells

We have investigated one mechanism by which pooled human IgG preparations for intravenous use (IVIg) selectively down-regulates lymphokine synthesis. Effects of IVIg on cytokine production were quantified at a cellular level by using an immunocytochemical staining technique. Pure T-lymphocyte preparations (from the peripheral blood of healthy adults) were separated by the use of magnetic beads and were then used in parallel experiments with unfractionated mononuclear cells (MNC). Cell activation was induced either by a combination of the protein kinase C activator, phorbol 12-myristate 13-acetate (PMA), and the calcium ionophore, ionomycin, or by direct ligation of the T-cell receptor, using immobilized anti-CD3 monoclonal antibody (MoAb). Cells were cultured in the presence or absence of IVIg and subsequently harvested and stained for the following cytokines: interleukin-2 (IL-2), interferon-γ (IFN-γ), tumour necrosis factor-β (TNF-β) and granulocyte–macrophage colony-stimulating factor (GM-CSF). Assessment of the frequencies of positively stained cells was performed by manual microscopy and by computerized image analysis. Activation by PMA/ionomycin or by immobilized anti-CD3 MoAb induced substantial lymphokine production in both MNC and in purified T cells. Addition of IVIg led to a diminished synthesis of all of the T-cell products studied in unfractionated MNC preparations, whereas production was maintained or occasionally increased in the purified T-cell preparations. These findings indicate that the immunomodulatory effect by IVIg on T-cell activation and lymphokine production was dependent on accessory cells.     

Subclass distribution of IgG and IgA antibody response to Pseudomonas pseudoalcaligenes in humans exposed to infected metal-working fluid

The subclass distribution of the IgG and IgA antibody response in serum was studied in humans exposed to aerosolized metal-working fluid containing Pseudomonas pseudoalcaligenes. This species was consistently found in concentrations of 10(8) bacteria per milliliter of metal-working fluid during 1 year of observation. No increased frequency of respiratory infections or discomfort was related to the exposure to the infected fluid. The antibody response to the bacterium consisted predominantly of IgG1 and IgG2 antibodies. IgG2 antibodies dominated the antibody response to the lipopolysaccharide of the bacterium. IgA1 and IgA2 antibodies were also found. Smokers had significantly reduced antibody levels of all subclasses compared with nonsmokers. The antibody levels in smokers did not differ from levels of the unexposed control group. Analyses of the total serum immunoglobulin concentrations with respect to subclasses revealed that the total IgG2 levels were also significantly reduced in smokers. In nonsmokers, the age of the individuals influenced the antibody levels of the IgG1, IgG2, IgA1, and IgA2 subclasses, the levels decreasing with increasing age. For smokers, the correlation between age and antibody levels was only obvious for IgG2 antibodies. Decreased IgG2 antibody levels in the smokers were also accompanied by decreased FEV1 values (p less than 0.01). Subclass analysis of the antibody response to P. pseudoalcaligenes demonstrated that the subclass pattern for the whole bacterium differed from the pattern of the major cell wall component, the lipopolysaccharide. The significance of qualitative and quantitative differences in the subclass antibody response is discussed.     

IVIg selectively and rapidly decreases circulating pathogenic autoantibodies in pemphigus vulgaris

BACKGROUND: Intraveneous immunoglobulin (IVIg) is increasingly used to treat pemphigus vulgaris (PV). The mechanism by which it does so is not known. The following study was conducted to confirm the effectiveness of IVIg for the acute control of active PV and to elucidate the mechanism by which it does. METHODS: Twelve patients with active and severe PV unresponsive to conventional therapy with high doses of systemic steroids together with or without a cytotoxic drug were treated with a single dose of IVIg (400 mg/kg/day for 5 days). All patients were concurrently given cyclophosphamide or azathioprine of not already on one of these two drugs. The primary end-points were healing of skin lesions, changes in serum levels of intercelular (IC) autoantibodies and in steroid doses one to 3 weeks after initiation of IVIg. RESULTS: Within 1 week of initiating IVIg the activity of PV was controlled in most cases. Within 3 weeks the average baseline dose of systemic steroid was reduced by 40%. Serum levels of IC antibodies rapidly declined by an average of 59% within 1 week of initiating IVIg and by 70% within 2 weeks. The decrease was selective, as the average serum levels of antibody to varicella-herpes zoster did not decrease in the 4 patients in whom they were measured. The decrease in IC antibodies was inversely related to serum levels of total inmmunoglobulin (IgG). The decrease in IC antibodies was not due to blocking factors in the IVIg preparation and was too rapid to be due to suppression of IgG synthesis, suggesting that it resulted from increased catabolism. CONCLUSIONS: IVIg can rapidly control active PV unresponsive to conventional therapy by causing a selective and very rapid decline in the autoantibodies that mediate the disease. We believe it does so by increasing the catabolism of all serum IgG antibodies, and that this results in a selective decrease in only abnormal autoantibodies as catabolized normal anti bodies are replaced by those present in the IVIg preparation. IVIg is the first treatment that achieves the ideal therapeutic goal in auto-antibody diseases, the selective removal of the pathogenic antibodies without affecting the level of normal antibodies.