In vitro IgM rheumatoid-factor production induced by tetanus toxoid

In vitro stimulation of lymphocytes from healthy donors with well-defined polyclonal B cell activators may elicit the production of rheumatoid factor (RF) as well as other autoantibodies. Antigen stimulation may also result in polyclonal B cell activation, but it is not known if RF production is a feature of this response. Therefore, peripheral blood mononuclear cells from 36 healthy volunteers previously immunized to tetanus toxoid (TT) were stimulated in vitro for 9 days with a conventional antigen, TT, or pokeweed mitogen, a standard polyclonal B cell activator. Culture supernatants were analyzed for total IgG, total IgM, and IgM RF by ELISA. TT-induced IgM RF production was observed in 10/36 experiments compared to 18/36 experiments in which cells were cultured with pokeweed mitogen, with a similar magnitude of response to these respective stimulants. The in vitro IgM-RF response to TT did not require a recent in vivo TT booster immunization and was observed at an antigen does that elicits polyclonal B cell activation but not IgG specific anti-TT antibody. TT-induced IgM RF responder cultures demonstrated higher levels of total IgG and total IgM production than cultures not secreting IgM RF in response to TT. These results indicate that IgM RF production is a concomitant of the polyclonal B cell response elicited by a conventional antigen. Unlike other model systems, this antigen-induced RF response was not mediated by the action of IgG antibody containing immune complexes.     

The immune response in the hamster. II. Studies on IgM

Hamster IgM has been isolated and characterized. The protein possessed unique antigenic determinants but also shared common determinants with the 7Sγ₁- and 7Sγ₂-globulin classes. These shared determinants were present on the F(ab′)₂ and Fab fragments of 7Sγ₂-globulin. The rapidly sedimenting (S_20,w = 20.7) IgM was dissociated into slowly sedimenting (≈ 7S) units after reduction and alkylation. Specific antibody formation in the IgM and IgG (7Sγ₁-globulin) classes appeared at similar times after immunization with protein antigens, although IgM antibody was only detectable for a short period. After immunization with antigen in Freund''s adjuvant, the serum concentration of IgM increased and remained at an elevated level even after disappearance of antibody to the immunizing antigen. Injection of adjuvant alone also increased the concentration of serum IgM, particularly after intraperitoneal administration of Freund''s incomplete adjuvant.     

Enhancement by the adjuvant, endotoxin, of an immune response induced in vitro

Effects of endotoxin on the immune response to sheep red cells added in vitro to spleen cell suspensions from unimmunized mice were studied. The optimal dose of endotoxin (1 μg/ml) gave a six-fold increase in the number of plaque-forming cells per 10⁶ viable cells, after 6 days of culture, if it was present from the 12th to the 24th hour after antigen. There was little or no enhancement when endotoxin was given at other times during the 6 days of culture. The response was depressed when the suspension was incubated with endotoxin before the addition of red cells. The periods of RNA and DNA synthesis were determined by adding tritiated uridine and tritiated thymidine, respectively, for 24-hour periods during the 6 days of culture. Synthesis of RNA occurred throughout the culture period whereas DNA synthesis was not detected before 24 hours of culture. We found that the adjuvant action of the endotoxin which was maximum during the 1st day of culture, was associated with an initial phase of RNA synthesis, before DNA synthesis could be detected.     

Biomaterial-induced alterations of neutrophil superoxide production.

Because periprosthetic infection remains a vexing problem for patients receiving implanted devices, we evaluated the effect of several materials on neutrophil free radical production. Human peripheral blood neutrophils were incubated with several sterile, lipopolysaccharide (LPS)-free biomaterials used in surgically implantable prosthetic devices: polyurethane, woven dacron, and velcro. Free radical formation as the superoxide (O2-) anion was evaluated by cytochrome c reduction in neutrophils that were exposed to the materials and then removed and in neutrophils allowed to remain in association with the materials. Neutrophils exposed to polyurethane or woven dacron for 30 or 60 min and then removed consistently exhibited an enhanced release of O2- after simulation via receptor engagement with formyl methionyl-leucyl-phenylalanine. Enhanced reactivity to stimulation via protein kinase C with phorbol myristate acetate, however, was not consistently observed. The cells evaluated for O2- release during continuous association with the biomaterials showed enhanced metabolic activity during short periods of association (especially with polyurethane and woven dacron). Although O2- release by neutrophils in association with these materials decreased with longer periods of incubation, it was not obliterated. These studies, therefore, show that several commonly used biomaterials activate neutrophils soon after exposure and that this activated state diminishes with prolonged exposure but nevertheless remains measurable. The diminishing level of activity with prolonged exposure, however, suggests that ultimately a depletion of reactivity may occur and may result in increased susceptibility to periprosthetic infection.     

HIV induced neuroendocrine alterations in AIDS patients as a co-factor of immune deficiency

HIV may induce subclinical neuroendocrine dysfunctions in some seropositive patients and these dysfunctions may be one of the co-factors that determine the pathogenesis of AIDS.     

Increased IgM and IgM immune complex-like material in the circulation of renal transplant recipients with primary cytomegalovirus infections.

Twelve of 60 consecutive adult recipients of cadaver kidney transplants had increased polyethyleneglycol (PEG) precipitable IgM immune complex-like material in their circulation in the first 4 months after transplantation. All 10 recipients with primary CMV and two of four with secondary CMV infections had significant elevations in PEG precipitable IgM that coincided with rises in their CMV antibody titres. Ultracentrifuge analysis demonstrated two peaks of PEG precipitable material with sedimentation rates of about 20S and 40S. Total IgM immunoglobulin levels also were increased in transplant recipients with CMV infections, but this was less specific and occurred in patients without CMV infections. The Clq binding assay, which is more sensitive for IgG than IgM containing complexes, was positive in only three of 10 patients with primary CMV and none of four with secondary CMV. Granular deposits of IgM, but not IgG, were detected in the glomeruli of six of seven transplants biopsied during CMV infection. The PEG-IgM assay was not influenced by rejection or prednisone therapy. Thus, transplant patients, who develop primary CMV infections, produce elevated levels of circulating IgM and IgM immune complex-like material. These findings may help to differentiate CMV infection from transplant rejection as well as to increase our understanding of the special pathogenic properties of CMV in transplant recipients.     

Role of natural and immune IgM antibodies in immune responses

IgM antibodies constitute the major component of the natural antibodies and is also the first class of antibodies produced during a primary antibody response. The IgM-type antibodies differ from other classes of antibodies in that they are predominantly produced by B1 cells, in the absence of apparent stimulation by specific antigens. In addition, IgM antibodies are mostly encoded by germline V gene segments and have low affinities but broad specificites to both foreign and self structures. New developments regarding the function of both immune IgM antibodies and natural IgM antibodies will be examined here.     

The role of IgM rheumatoid factor in experimental immune vasculitis.

The effect of IgM rhematoid factor (RF) on reversepassive cutaneous Arthus reaction in rats was studied. The RF was obtained from the serum cryoglobulin of a patient with symptoms of purpura, arthralgia and digital gangrene. The cryoglobulins was of IgG-IgM type and when given i.v it induced a prompt hypocomplementaemia in experimental animals. The purified RF also induced low serum complement levels when injected i.v. along with complexes of non-complement-fixing, aggregated IgG. A reverse passive Arthus reaction was induced by intradermal injection of IgG anti-bovine serum albumin (BSA), followed by an i.v. dose of antigen (Ag). The cutaneous inflammatory reaction was aggravated by simultaneous administration of IgM RF intradermally, but not by IgM without antibody (Ab) properties. Intradermal injection of low concentrations of non-complement-fixing IgG anti-BSA, along with normal human IgM, followed by i.v. injection of BSA, resulted in a complete lack of cutaneous inflammation. At higher Ab concentrations there was only a mild inflammation. However, when IgM RF was substituted for normal IgM and injected with non-complement-fixing anti-BSA, an effective reverse passive cutaneous Arthus reaction and vasculitis was induced. The inflammatory response was greatly suppressed by decomplementation of animals by cobra venom factor. This study provides evidence favouring an inflammatory, complement-dependent role for RF in vasculitis.     

Estradiol impairs the Th17 immune response against Candida albicans

Candida albicans is a commensal opportunistic pathogen that is also a member of gastrointestinal and reproductive tract microbiota. Exogenous factors, such as oral contraceptives, hormone replacement therapy, and estradiol, may affect susceptibility to Candida infection, although the mechanisms involved in this process have not been elucidated. We used a systemic candidiasis model to investigate how estradiol confers susceptibility to infection. We report that estradiol increases mouse susceptibility to systemic candidiasis, as in vivo and ex vivo estradiol-treated DCs were less efficient at up-regulating antigen-presenting machinery, pathogen killing, migration, IL-23 production, and triggering of the Th17 immune response. Based on these results, we propose that estradiol impairs DC function, thus explaining the increased susceptibility to infection during estrus.     

Cardiac matrix alterations induced by adriamycin.

Adriamycin is toxic to humans and animals and causes cardiac lesions involving myocytes and the interstitial tissue. The present study used a single injection of adriamycin in rats. Focal loss of myocardial interstitial collagen occurred 2 weeks after a single injection of adriamycin. These foci become larger and more frequent through 6 weeks. Individual variation in response is evident after periods longer than 6 weeks. Concomitant with the focal loss is deposition of collagen in an abnormal distribution. Rather than the normal matrix being present, scars appear. The number and size of these scars is subject to variation from animal to animal. The collagen matrix loss is evident in some animals at 15 weeks after injection. These observations, coupled with the results of other studies on the myocardial collagen matrix, support the hypothesis that adriamycin cardiotoxicity is mediated in part by an affect on the collagen matrix.     

Enhancement of humoral and protective immune response induced by live-attenuated Salmonella typhi by ampicillin

Efficacy of live-attenuated Salmonella vaccines delivered by the mucosal route is limited by the dose and interference from mucosal flora of the alimentary tract. In a mouse model, the total antibody response towards lipopolysaccharide of S. typhi was significantly enhanced at day 21 post-immunization with live-attenuated S. typhi (Ty21a) when ampicillin was concomitantly administered (p<0.005), and the lethal dose 50 of mice in the ampicillin and control groups immunized with Ty21a after wild-type S. typhi challenge on day 24 was 4x10(7) and 1x10(7), respectively. The faecal bacterial counts of the ampicillin group at days 1 and 3 were significantly lower than those of the control group (p<0.01 and <0.05). On day 1, the number of mice with > or =10 Ty21a colonies isolated from the spleen was significantly higher in the ampicillin group than the control group (p<0.05). Furthermore, on the same day, Ty21a was isolated from the faeces of three mice from the ampicillin group, but only one from the control group. We conclude that ampicillin may have enhanced the humoral and protective immune responses by giving the Ty21a a selective advantage over the normal bacterial flora. This concept of antibiotic enhancement of immunization could have important implications for other live-attenuated vaccines, as well as the delivery of microbial antigens and DNA vaccines by live-attenuated Salmonella carriers.     

Humoral immune response in patients with IgA and IgM glomerulonephritis.

A single dose of inactivated mumps virus vaccine was administered to male patients with IgA glomerulonephritis (IgA-GN), IgM glomerulonephritis (IgM-GN) and to healthy males. Antibodies to mumps virus were determined using an enzyme-linked immunosorbent assay. Patients with IgA-GN showed a higher and more sustained IgG and IgA antibody response compared to patients with IgM-GN or healthy controls. Before vaccination, patients with IgM-GN had higher levels of IgG antibodies than the controls or those with IgA-GN. However, the IgA antibody and IgG responses after vaccination were low. IgM antibody responses did not vary among the groups studied. It is concluded that patients with IgA-GN are high responders for IgA and IgG antibody production. Patients with IgM-GN are low responders, especially for IgA antibody.     

Nifurtimox-induced alterations in the cell-mediated immune response to PPD tin guinea-pigs.

Positive skin reactions to PPD in guinea-pigs immunized with Freund's complete adjuvant (FCA) were reversed after treatment with 10 mg/kg/day nifurtimox for 12 days. The in vitro migration of peripheral blood leucocytes from FCA-immunized guinea-pigs was inhibited with PPD, but it returned to normal values after nifurtimox treatment. Furthermore, the cell-free supernatant from PPD-stimulated lymphocytes from FCA-immunized nifurtimox-treated guinea-pigs did not inhibit the migration of normal cells. Thus the administration of nifurtimox impaired the specific cell-mediated immune response to PPD both in vivo and in vitro.     

Target-cell membrane alterations induced by lymphotoxin. Ultrastructural observations.

Upon in vitro stimulation by antigens or mitogens, lymphocytes release a series of lymphokines. One such lymphocyte mediator is lymphotoxin, which appears to be responsible for in vitro lymphocyte-mediated cytolysis. Employing immuno-electron microscopy with ferritin- or peroxidase-labeled antibody, we observed patchy localization of the mediator on the plasma membranes of target L cells exposed to lymphotoxin, often in areas overlying a microfilament web. When studying lymphotoxin-affected cells by electron microscopy of freeze-fracture replicas, we observed aggrlasma membrane, with intervening areas which were frequently particle free. Sometimes the affected cells revealed plasma-membrane lesions suggesting intramembranous "blisters."     

Characterization of immune complexes containing cytomegalovirus-specific IgM antibodies following a kidney graft.

In order to demonstrate the viral specificity of IgM-containing immune complexes (IgM-CIC) detected by a C1q assay in renal allograft recipients developing a CMV infection, a technique is described allowing: 1) the dissociation of IgM-CIC by action of an acid buffer, and 2) the characterization of the viral specificity of IgM antibodies released by this treatment. This step was performed by ELISA and Western Blot. When technique was applied to the follow-up of a renal allograft recipient developing a recurrent CMV infection within 2 months post-graft, it was found that the IgM-CIC detected on the day of the graft were not CMV-specific, whereas the IgM-CIC detected during the second month after transplantation contained CMV-specific IgM antibodies. These CMV-specific IgM-CIC were detected as early as the urinary viral excretion. It was shown by Western Blot analysis that these IgM antibodies reacted with a 45-47 kDa viral polypeptide which is a viral target for specific humoral response at the early phase of CMV infection.