Occurrence of antibodies to Borrelia burgdorferi in patients with nonspirochetal subacute bacterial endocarditis

OBJECTIVE

To determine the prevalence and specificity of antibodies to Borrelia burgdorferi in patients with nonspirochetal subacute bacterial endocarditis and assess whether increased levels of antibodies to B. burgdorferi were attributable to rheumatoid factor.

DESIGN

Retrospective case-control study.

SETTING

Urban referral center in an area devoid of infected ticks as a source of endocarditis sera.

PATIENTS

Sera from 30 consecutive patients with culture-proven subacute endocarditis between 1979 and 1981 were compared with 30 control sera collected between 1989 and 1990. In addition, sera from 20 consecutive patients with rheumatoid arthritis who were positive for rheumatoid factor were collected between 1991 and 1992. Sera were compared with a convenience sample from 15 patients who met the criteria for Lyme disease.

MEASUREMENTS

Antibodies to B. burgdorferi were assessed by enzyme-linked immunosorbent assay (ELISA) and immunoblot analysis. IgM rheumatoid factor was quantified using solid-phase radioimmunoassay or latex agglutination techniques.

RESULTS

Thirteen of 30 patients with endocarditis (43%) compared with 3 of 30 normal controls (10%) had increased levels of antibodies to B. burgdorferi (P < 0.01). Of these 13 patients, only 1 had an immunoblot consistent with previous infection. The others had nonspecific immunoblots: 5 showed isolated 60-kd reactivity; 1 patient had isolated 41-kd reactivity; and 6 had no bands of reactivity. Immunoblots of the 3 controls with increased antibodies showed only isolated 41-kd reactivity. Thus, the specificity of the B. burgdorferi antibody test in patients with endocarditis was only 60% (95% CI, 42% to 78%), compared with 90% (CI, 79% to 100%) in controls. No correlation was noted between IgM rheumatoid factor and antibodies to B. burgdorferi in patients with endocarditis (r = 0.2; P > 0.2). Only 1 of 20 patients with rheumatoid arthritis without known bacterial infections had antibodies to B. burgdorferi.

CONCLUSIONS

Although a positive ELISA test for B. burgdorferi may be a "true positive," a positive serologic test alone does not ensure that the clinical problem is due to Lyme borreliosis. Cross-reactive antibodies to shared epitopes between B. burgdorferi and the endocarditis organism may account for the high false-positive results.

HLA-B27/microbial mimicry: an in vivo analysis

The association between three major spondyloarthritic diseases, ankylosing spondylitis, Reiter's syndrome, and reactive arthritis, and the major histocompatibility complex (MHC) class 1 antigen HLA-B27 is well documented. The hypothesis of cross-reactivity between HLA-B27 and the antecedent infection-causing Gram-negative pathogens such as Salmonella, Shigella and Yersinia has been suggested by in vitro studies employing monoclonal antibodies. We have examined the possibility of such cross-reactivity in vivo using various rabbit immune sera and patient sera as the source of cross-reacting antibody. Mouse L cells were transfected with HLA-A3 or HLA-B27 and used as a source of antigen. Western blot analysis employing denatured antigen, FACS analysis employing native antigen and immunoprecipitation studies were undertaken to detect cross-reacting antibodies generated in vivo to HLA-B27 antigen. Antibodies generated in vivo by infection in patients or immunization in animals against arthritogenic bacteria did not demonstrate any cross-reactivity with HLA-B27 by any of the methods used. As defined by the humoral immune response, molecular mimicry appears unlikely to explain the role of B27 in the pathogenesis of reactive arthritis.

Immunoepidemiology of post-Salmonella reactive arthritis in a cohort of women

Following a foodborne outbreak of Salmonella dysentery in a group of 79 women and 4 men, 6 individuals were found to have reactive arthritis (ReA). None of the affected individuals had the classical genetic marker HLA B27 although 2 of the 6 had CREG antigens. IgA antibodies to the lipopolysaccharide of the causative organism, Salmonella heidelberg, were found to be elevated in those patients with active ReA compared to those with inactive ReA or those who had dysentery but did not develop ReA. The lymphocyte proliferative response to both PHA and the whole S. heidelberg organism was impaired in the patients with ReA (active or inactive) compared with the non-ReA patient controls. In this predominantly female outbreak of Salmonellosis, the development of ReA lacked an association with HLA class I antigens commonly recognized.

HLA-B27 expression modulates gram-negative bacterial invasion into transfected L cells

The mechanism by which HLA-B27 confers genetic susceptibility to the seronegative spondyloarthropathies ankylosing spondylitis, Reiter's syndrome, and reactive arthritis, is not well understood. The current concept of an extraarticular bacterial infection functioning as the triggering event in a genetically susceptible host suggests the possibility of direct microbial-MHC interaction. We have addressed the role of HLA-B27 in microbial-host cell interaction by examining invasion by putatively arthritogenic gram-negative bacteria. Target cells used were murine L cells transfected with HLA-B27, HLA-A3, HLA-A2, HLA B44, HLA B18, or pSV2neo vector alone. Relative to the pSV2neo control and the HLA-A3 transfectant, HLA-B27-transfected cells demonstrated a consistent decrease in invasion for each of the following pathogens: Salmonella typhimurium (45 +/- 2% decrease), Shigella sonnei (53 +/- 13% decrease), Shigella flexneri (45 +/- 5% decrease), and enteroinvasive Escherichia coli (57 +/- 8% decrease). This decrease was specific for the HLA B27-transfected L cells and was not observed in the other B allele transfectants. The decreased invasion in the HLA-B27 transfectants is not the result of either altered endogenous mouse class I expression as a result of human class I transfection or increased intracellular bacterial killing within the B27 transfectants. There was an inverse relationship between the amount of surface expression of HLA-B27, as measured by FACS, and the degree of invasion. Blocking of surface B27 Ag with anti-B27 mAb augmented bacterial invasion in the B27 transfectants. These studies demonstrate a novel bacterial-B27 interaction that may have relevance to the pathogenesis of B27-related arthritis.

HLA-B27 expression modulates gram-negative bacterial invasion into transfected L cells

The mechanism by which HLA-B27 confers genetic susceptibility to the seronegative spondyloarthropathies ankylosing spondylitis, Reiter's syndrome, and reactive arthritis, is not well understood. The current concept of an extraarticular bacterial infection functioning as the triggering event in a genetically susceptible host suggests the possibility of direct microbial-MHC interaction. We have addressed the role of HLA-B27 in microbial-host cell interaction by examining invasion by putatively arthritogenic gram-negative bacteria. Target cells used were murine L cells transfected with HLA-B27, HLA-A3, HLA-A2, HLA B44, HLA B18, or pSV2neo vector alone. Relative to the pSV2neo control and the HLA-A3 transfectant, HLA-B27-transfected cells demonstrated a consistent decrease in invasion for each of the following pathogens: Salmonella typhimurium (45 +/- 2% decrease), Shigella sonnei (53 +/- 13% decrease), Shigella flexneri (45 +/- 5% decrease), and enteroinvasive Escherichia coli (57 +/- 8% decrease). This decrease was specific for the HLA B27-transfected L cells and was not observed in the other B allele transfectants. The decreased invasion in the HLA-B27 transfectants is not the result of either altered endogenous mouse class I expression as a result of human class I transfection or increased intracellular bacterial killing within the B27 transfectants. There was an inverse relationship between the amount of surface expression of HLA-B27, as measured by FACS, and the degree of invasion. Blocking of surface B27 Ag with anti-B27 mAb augmented bacterial invasion in the B27 transfectants. These studies demonstrate a novel bacterial-B27 interaction that may have relevance to the pathogenesis of B27-related arthritis.

The role of infection in chronic arthritis

The hypothesis that in arthritis an infectious agent functions at least as a triggering factor, if not a perpetuating one, has inspired decades of clinical investigation. Increasingly these studies are using more sophisticated tools of molecular biology which are applied in microbiology, immunology and immunogenetics. In the spondyloarthropathies these newer techniques are defining the molecular bases for the interplay of microbial antigen and the MHC antigens. The clues to provocative antigens are still elusive, although the class II MHC susceptibility is becoming clarified. Both viral and mycobacterial antigens are being examined in rheumatoid arthritis, but definitive answers are still lacking.

Interplay of microbe and major histocompatibility complex: a family study

We describe a 24-year-old man who developed reactive arthritis (ReA) after a dysenteric illness caused by Salmonella hadar. Serologic tests suggested recent exposure of family members to Salmonella. All members of the family were HLA-B27 positive, but no other family member developed acute ReA, although 2 of them had clinical evidence of previously existing B27 associated arthritis.

Infectious etiology of rheumatoid arthritis

The infectious etiology of rheumatoid arthritis has been a long-standing hypothesis and in recent years is being examined with greater sophistication and scientific rigor. Synovitis may result indirectly from infection by the deposition of circulating immune complexes, by molecular mimicry, by in situ antigen deposition, or by arthritogenic toxins. Of candidate pathogens, recent interest has focused on mycobacterial HSP, EBV, and parvovirus B19. There is circumstantial evidence to support a link between each of these microorganisms and RA but presently all fall short of definitive proof of causality. It is anticipated that clearer answers may be forthcoming on this perplexing and intriguing question with the application of molecular biologic techniques to the study of synovial tissues.

Antigens, the gastrointestinal tract, and arthritis

There are a variety of forms of arthritis that appear causally related to a primary process in the gastrointestinal tract. Resolving the normal immune response to gut-acquired antigens of microbial and dietary origin can guide our understanding of the protean manifestations of the interface of arthritis and enteritis.

Autoantibodies to the HLA-B27 sequence cross-react with the hypothetical peptide from the arthritis-associated Shigella plasmid

We previously reported elevated serum antibody levels to a peptide representing the HLA-B27 polymorphic region (B27 peptide) in HLA-B27(+) ankylosing spondylitis (AS) patients. A plasmid (pHS-2) isolated from arthritogenic Shigella flexneri strains had been shown to encode an amino acid sequence homologous to HLA-B27. Rabbit antibody to this sequence (pHS-2 peptide) strongly cross-reacted with B27 peptide and, to a much lesser extent, with Klebsiella nitrogenase peptide. Serum antibody levels to pHS-2 peptide were studied in 160 spondylarthropathy patients. 12 of 115 (10.4%) AS patients, 2 of 45 (4.4%) patients with Reiter's syndrome or reactive arthritis as well as 6 of 147 (4.1%) normal controls were shown to have elevated anti-pHS-2 peptide antibodies. Antibody levels to B27 and pHS-2 peptides were significantly correlated in 134 HLA-B27(+) patients (r = 0.333, P less than 0.001). 13 of 15 affinity-purified anti-B27 peptide antibodies from patients strongly cross-reacted with pHS-2 peptide, whereas only 3 weakly cross-reacted to nitrogenase peptide. Leucine appeared to be a critical residue for this cross-reaction. AS patients' anti-B27 peptide antibodies reacted with HLA-B27 transfected L cells. These results may suggest that pHS-2 peptide more efficiently "mimics" B27 peptide than does nitrogenase peptide. Involvement of pHS-2 in pathogenesis of spondylarthropathy through molecular mimicry mechanisms requires further study.

Prevalence of tendinitis and related disorders of the upper extremity in a manufacturing workforce

A cross sectional survey of a randomly selected population of 2,261 textile workers form an overall population of 8,539 eligible workers was performed to evaluate the prevalence of tendinitis in related upper extremity disorders. Of the sample, 2,047 respondents (91.3%) participated in a nurse screening history and examination: 1,091 (53%) had no upper extremity symptoms or abnormalities on examination; 959 (47%) with positive findings were examined by trained physicians. Of these, 347 (36.5%) were found to have no abnormality, whereas, 548 (57.3%) workers were assigned a diagnosis. Of these 227 were considered to fall into the categories of tendinitis (n = 69) or related disorders (n = 158). The projected prevalence of tendinitis and related disorders for the overall group was 11.6% (carpal tunnel syndrome 1.1%, epicondylitis 2.0%, tendinitis 3.5%, shoulder condition 2.3%, ganglion 2.3%, neck conditions 4.0%). Tendinitis was less frequent in the older age group and those employed for a longer time. The prevalence of tendinitis was found to be statistically higher in physically demanding job categories. Ninety-four percent of ailments were of mild or moderate severity. Although our study provides prevalence data for these conditions in a large manufacturing workforce across several job categories.

Substance P and arthritis: analysis of plasma and synovial fluid levels

The uncadecapeptide substance P (SP), which is localized in peripheral and central terminals of afferent nerve fibers with polymodal nociceptors, has recently been implicated as having a neurogenic, inflammatory role in experimental arthritis. We used a radioimmunoassay to measure SP levels in plasma and synovial fluid samples from patients with rheumatoid arthritis (RA), osteoarthritis (OA), Reiter's syndrome (RS), and posttraumatic arthritis, as well as in plasma samples from 13 normal subjects. Plasma SP levels in RS patients exceeded levels in RA and OA patients, which in turn exceeded levels in posttrauma patients and in normal subjects. Synovial fluid SP levels exceeded respective plasma levels for all groups, except in RS patients, in whom the plasma level was not significantly different from that in synovial fluid. SP levels in synovial fluid of RA, OA, and RS patients did not differ significantly from each other, but the level in posttrauma patients was higher than in all other groups (P less than 0.005). These studies demonstrate localized intraarticular SP release, and significant plasma/synovial fluid SP concentration gradients in several forms of arthritis.

Neuromodulation of synovitis: capsaicin effect on severity of experimental arthritis

This study addresses the effect of capsaicin on the severity of inflammation in experimental arthritis in the cat. Animals were sensitized with methylated bovine serum albumin (mBSA) and sequential serum antibody levels measured by enzyme-linked immunosorbent assay (ELISA). Synovitis was induced by intra-articular injection of mBSA. Histopathology revealed marked inflammatory cell infiltration and synovial cell hypercellularity, in comparison with the saline-injected control joint which showed no synovitis. In animals given intra-articular capsaicin concurrently with mBSA, there was consistently a diminution in the severity of inflammation compared with contralateral joints receiving mBSA alone. In this experimental system capsaicin appears to moderate the severity of inflammation in feline antigen-induced arthritis.

HLA class I-related impairment in IL-2 production and lymphocyte response to microbial antigens in reactive arthritis

The contribution of certain Gram-negative bacteria and host HLA class I Ag to the development of reactive arthritis (ReA)3 has strong epidemiologic support but the pathogenesis of the arthritis is unknown. An outbreak of Salmonella typhimurium afforded the opportunity to compare the immune response to the organism between those who developed ReA (ReA+, n = 11) with those who did not (ReA-, n = 12). Of the 11 ReA+ patients, 4 were B27-positive and 6 were B7-positive; of the ReA- patients none was B27- or B7-positive. The causative pathogen S. typhimurium phage 22 was used to examine PBL proliferation by [3H]thymidine incorporation. Impairment in lymphocyte response to S. typhimurium in ReA+ compared with ReA- was demonstrated by: i) lower stimulation index (1.9 +/- 0.3 for ReA+, 5.7 +/- 0.6 for ReA-, p less than 0.01); ii) lower in vitro Ig production; and iii) lower Ag-induced IL-2 production. Mixing experiments did not demonstrate a soluble suppressor factor in ReA+ supernatants. Thus, after infection with S. typhimurium there is an impairment in cellular immunity that has correlates in immunogenetic and clinical features of the infected population.

HLA class I-related impairment in IL-2 production and lymphocyte response to microbial antigens in reactive arthritis

The contribution of certain Gram-negative bacteria and host HLA class I Ag to the development of reactive arthritis (ReA)3 has strong epidemiologic support but the pathogenesis of the arthritis is unknown. An outbreak of Salmonella typhimurium afforded the opportunity to compare the immune response to the organism between those who developed ReA (ReA+, n = 11) with those who did not (ReA-, n = 12). Of the 11 ReA+ patients, 4 were B27-positive and 6 were B7-positive; of the ReA- patients none was B27- or B7-positive. The causative pathogen S. typhimurium phage 22 was used to examine PBL proliferation by [3H]thymidine incorporation. Impairment in lymphocyte response to S. typhimurium in ReA+ compared with ReA- was demonstrated by: i) lower stimulation index (1.9 +/- 0.3 for ReA+, 5.7 +/- 0.6 for ReA-, p less than 0.01); ii) lower in vitro Ig production; and iii) lower Ag-induced IL-2 production. Mixing experiments did not demonstrate a soluble suppressor factor in ReA+ supernatants. Thus, after infection with S. typhimurium there is an impairment in cellular immunity that has correlates in immunogenetic and clinical features of the infected population.

Internuclear ophthalmoplegia in giant cell arteritis

Ophthalmoplegia from ischemia to peripheral ocular motor nerves or muscles may complicate the course of giant cell arteritis (GCA). Although brainstem ischemia is known to occur in GCA, internuclear ophthalmoplegia has not been described. Two cases of biopsy-proven GCA are described in which internuclear ophthalmoplegia resulted from brainstem ischemia. Embolization from thrombosed extradural segments of inflammed vertebral arteries, or arteritis of brainstem perforating vessels may account for brainstem infarction. Rapid tapering of steroids was temporally related to brainstem infarction in both cases.

Plasma substance P levels in fibrositis

The mechanism of pain in the fibrositis syndrome is unknown. We measured plasma levels of substance P in 32 patients with fibrositis and 26 sex and age matched controls using a radioimmunoassay. The mean plasma level of substance P in the patients with fibrositis was 371 +/- 91 pg/ml and in controls 397 +/- 84 pg/ml (p = NS). We conclude that determination of plasma levels of substance P in fibrositis is of no diagnostic value. This does not exclude the possible role of substance P as a neurotransmitter in the fibrositis syndrome.

Postdysenteric reactive arthritis. A clinical and immunogenetic study following an outbreak of salmonellosis

Following an outbreak of foodborne gastroenteritis caused by Salmonella typhimurium, questionnaires were sent to affected individuals and then to the family physicians of any who experienced extra-enteric complications. Of 260 individuals infected with S typhimurium for whom adequate data were obtained, 19 patients developed joint disease (7.3%). All were men; the mean age +/- SD was 39.3 +/- 1.6 years. Among the 16 patients for whom this information was available, the interval from the onset of diarrhea to the onset of joint pain was less than 7 days in 7, 8-21 days in 2, and greater than 21 days in 7. There was a significantly longer duration of diarrhea in those patients with joint disease (mean +/- SEM 15.2 +/- 2.6 days) than in those without complications (10.0 +/- 1.1 days) (P less than 0.01). The joint disease was monarticular in 3 patients and polyarticular in 16. The joints most commonly affected were the elbow (47%), wrist (47%), knee (42%), low back (32%), and shoulder (32%). Six of the 19 patients had at least 1 extraarticular feature: ocular (5 patients), mucosal (1 patient), urethral (2 patients), or cutaneous (1 patient). Of these 19 patients, 11 were located and agreed to HLA typing. Four were positive for HLA-B27, 6 were HLA-B7 positive, and 1 had HLA-Bw60. Of the 4 B27 positive patients, 3 were DR1 positive; of the 6 B7 positive patients, 5 were DR2 positive.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunogenetic aspects of host immune response

The central role of histocompatibility leukocyte antigens (HLA) class II molecules in antigen presentation has received great attention in recent years, yet class I molecules have been defined as primarily functioning as a restriction element for cytotoxic T cell killing of virus-infected cells. Extensive clinical evidence, however, indicates that the HLA class I genes are strongly associated with nonseptic complications of enteric and genitourinary bacterial infections. Ninety percent of patients with Reiter's syndrome and reactive arthritis are positive for HLA-B27, yet the mechanism of disease susceptibility conferred by this gene remains obscure. Hypotheses concerning this interaction include (i) class I antigens functioning as receptors for microbial antigens; (ii) class I antigens expressing determinants that cross-react with microbial antigens; and (iii) class I genes controlling immunoregulatory functions that dictate qualitative differences in immune response to pathogenic organisms. These hypotheses await formal testing and hold great promise for understanding immunogenetic control of immune responses in general.

Immunochemical analysis of immune response to Chlamydia trachomatis in Reiter's syndrome and nonspecific urethritis

Chlamydia trachomatis (Ct) has been proposed as a causative agent in Reiter's syndrome (RS) when an infection occurs in a susceptible host. To assess whether this susceptibility is reflected in a characteristic humoral immune response we compared patients with complicated (RS) and uncomplicated courses of nonspecific urethritis (NSU). Geometric mean titres of antibodies to C. trachomatis by immunofluorescence were 89.6 for RS, 80.0 for NSU and 16.0 for normals. 125I-Protein A probing of immunoblotted antigens of C. trachomatis revealed no band unique to RS. 125I-anti-IgA probing of immunoblots demonstrated reactivity with the 59,000 dalton antigen in 11/11 RS and 2/6 NSU. The major outer membrane protein of C. trachomatis (40,000 daltons) bound immunoglobulin nonspecifically. There was no clearly differentiating feature between HLA-B27-positive and B27-negative RS. One sequentially studied patient revealed an augmentation in synovial fluid IgA reactivity during the course of disease. No pattern of humoral immune response to C. trachomatis could be regarded as specific for RS nor for HLA B27-positivity. The study did not identify a Reiter's-specific antigen in C. trachomatis but demonstrates the usefulness of applying blotting techniques to population studies of HLA modulation of immune response to infectious agents.

Arthritis and enteritis--an interface of protean manifestations

We live in tenuous proximity to a vast array of microbial agents that inhabit the balanced ecosystem of the gut. When an alteration in that balance occurs our immune system can be challenged abruptly with pathogens expressing microbial antigens that may form immune complexes or that may induce autoimmunity by cross-reactivity with host endogenous antigens. Toxins and proteolytic enzymes, normally limited to bowel lumen, may evade local mucosal defences and effect systemic inflammatory responses. Understanding the pathogenic events behind arthritis related to GI pathology will provide insight not only into this important group of diseases but also into fundamental mechanisms underlying other forms of inflammatory joint disease which remain of unknown origin.

Analysis of serum and synovial fluid IgA in Reiter's syndrome and reactive arthritis

The presumed antecedent infection which precedes Reiter's syndrome and reactive arthritis is frequently across a mucosal surface, and IgA immune responses may play a role in this process. Twelve of 29 patients with these conditions demonstrated elevation in serum IgA levels, and serum IgA levels in the postdysentery group (mean 3.21 g/liter +/- 1.27) were higher (P less than 0.01) than those in the posturethritis group (mean 2.40 g/liter +/- 0.80). In 10 of the 12 patients, IgA was the only immunoglobulin increased. There was no evidence of activation of complement in serum or synovial fluid. Using a complement-dependent assay, we were unable to demonstrate circulating IgA immune complexes. Sucrose density gradient ultracentrifugation analysis was used to assess IgA immune complexes in a non-complement-dependent manner. IgA of 11s was in fact demonstrated by this technique but appeared to be polymeric IgA on the basis of specific binding of secretory component and resistance to acid dissociation. IgA rheumatoid factor was not present. Synovial fluid revealed levels of polymeric IgA higher (mean 56.7% +/- 12.9) than did serum (23.7% +/- 13.9, P less than 0.001) despite higher levels of total IgA in serum than in synovial fluid (synovial fluid:serum ratio of IgA, mean 0.53 +/- 0.11). Although elevation in serum IgA in postdysenteric arthropathies suggests mucosal acquisition of antigen, the study does not implicate IgA circulating immune complexes in the pathogenesis of these diseases.

Analysis of immune complexes in rheumatoid arthritis for Epstein-Barr virus antigens reveals cross-reactivity of viral capsid antigen and human IgG

We recently defined the immunochemical characteristics of immune complexes (IC) isolated from synovial fluid (SF) of patients with rheumatoid arthritis with the use of Western blot analysis. In the present study, we probe for exogenous antigens in the IC by examining the specificity of antisera raised against the IC. Anti-IC antisera demonstrated strong reactivity against the viral capsid antigen (VCA) of Epstein Barr virus (EBV), which was not explained by preimmune reactivity, polyclonal B cell activation, or Fc-mediated binding in the immunofluorescence or ELISA systems used to measure antibody titers. However, comparable anti-VCA reactivity was detected in antisera raised against non-rheumatoid SF. This phenomenon was not due to antigen since monoclonal anti-VCA antibody probing the IC by Western blot detected only IgG, nor to idiotype/anti-idiotype interaction since normal IgG absorbed out the anti-VCA reactivity. A monoclonal anti-VCA antibody competitively inhibited the binding of anti-IgG to IgG, and Fc fragment of IgG competitively inhibited the monoclonal antibody binding to VCA. No relationship between IgG anti-VCA antibody and IgG rheumatoid factor could be demonstrated. These data demonstrate an unexpected cross-reactivity of Fc fragment of IgG and VCA of EBV through the analysis of SF IC.

Analysis of immune complexes in rheumatoid arthritis for Epstein-Barr virus antigens reveals cross-reactivity of viral capsid antigen and human IgG

We recently defined the immunochemical characteristics of immune complexes (IC) isolated from synovial fluid (SF) of patients with rheumatoid arthritis with the use of Western blot analysis. In the present study, we probe for exogenous antigens in the IC by examining the specificity of antisera raised against the IC. Anti-IC antisera demonstrated strong reactivity against the viral capsid antigen (VCA) of Epstein Barr virus (EBV), which was not explained by preimmune reactivity, polyclonal B cell activation, or Fc-mediated binding in the immunofluorescence or ELISA systems used to measure antibody titers. However, comparable anti-VCA reactivity was detected in antisera raised against non-rheumatoid SF. This phenomenon was not due to antigen since monoclonal anti-VCA antibody probing the IC by Western blot detected only IgG, nor to idiotype/anti-idiotype interaction since normal IgG absorbed out the anti-VCA reactivity. A monoclonal anti-VCA antibody competitively inhibited the binding of anti-IgG to IgG, and Fc fragment of IgG competitively inhibited the monoclonal antibody binding to VCA. No relationship between IgG anti-VCA antibody and IgG rheumatoid factor could be demonstrated. These data demonstrate an unexpected cross-reactivity of Fc fragment of IgG and VCA of EBV through the analysis of SF IC.

Arthritis, vasculitis, and cryoglobulinemia associated with relapsing hepatitis A virus infection

Hepatitis A virus, unlike hepatitis B virus, has rarely been associated with extrahepatic features. Two patients developed relapsing hepatitis A complicated by arthritis in both cases and cutaneous vasculitis in one. Both patients had cryoglobulinemia, with cryocrit values of 4.3% and 8.6%. Serologic studies showed that the cryoglobulin consisted of polyclonal IgM and IgG. The washed cryoglobulin was analyzed by sucrose density gradient ultracentrifugation under neutral (pH 7.4) and acidic (pH 2.8) conditions. Enzyme-linked immunosorbent assay techniques were used to characterize the native and dissociated cryoglobulin. The cryoglobulin contained acid-dissociable IgG complexes greater than 19S, and high molecular weight rheumatoid factors of both IgG and IgM isotypes that could be dissociated to 7S and 19S forms, respectively. Dissociation of the cryoglobulin augmented 7S anti-hepatitis A virus IgG 2.27-fold, but augmented total 7S IgG only 1.12-fold, suggesting enrichment of antiviral antibody in the cryoglobulin.

Aseptic arthritis in a man with toxic shock syndrome

Synovitis in toxic shock syndrome (TSS) is an unusual finding. A 31-year-old man presented with pain and swelling in both knees and was found to have TSS, secondary to a septic bursitis caused by Staphylococcus aureus. Immune complexes were not detected in serum or synovial fluid, and the S aureus was not recovered from the inflamed joints. Antibodies against the TSS toxin-1 were detected in serum and synovial fluid, but in lower levels than would be seen in a normal control serum. Complement studies implicated alternative pathway activation by a marked diminution in C3 levels compared with C4 levels, and by lower levels of factor B than would be found in other inflammatory joint diseases. The diagnostic dilemma posed by TSS in a man is discussed.

Molecular mimicry in Reiter's syndrome: cytotoxicity and ELISA studies of HLA-microbial relationships

The pathogenic links between HLA antigens, certain bacterial infections and arthritis have not yet been characterized. The hypothesis of cross-reactivity between HLA B27, the marker of disease susceptibility for these disorders, and the provocative microorganism has been suggested by studies of Klebsiella and ankylosing spondylitis. The present study examines the possibility of molecular mimicry between HLA B27 and two organisms implicated more directly in reactive arthritis, Yersinia enterocolitica and Chlamydia trachomatis. Antibodies against these organisms were obtained both from patients and from antisera raised in rabbits. Neither source of antibacterial antibody was specifically cytotoxic for HLA B27-positive lymphocytes, even when the target cells were derived from patients with recent infections due to these organisms. In addition, monoclonal antibodies against HLA B27 (M1 and M2) showed no reactivity with antigens from these organisms in an ELISA system. These data do not support the notion of molecular mimicry as being the basis of immunogenetic susceptibility to reactive arthritis and Reiter's syndrome following infections with Y. enterocolitica and C. trachomatis.

Alpha 2-plasmin inhibitor-plasmin complexes in synovial fluid

The role of the fibrinolytic enzyme system in inflammatory joint disease has been addressed by several experimental approaches. In our study we examined synovial fluid (SF) in several different diseases for alpha 2-plasmin inhibitor-plasmin complexes by an enzyme linked immunosorbent assay (ELISA). These complexes are present in both rheumatoid and nonrheumatoid SF, with highest levels seen in septic arthritis. Thus the plasminogen system is intact in inflammatory SF, and plasmin may play a role in the local inflammatory process.

Characterization of sequential immune complexes in infective endocarditis by Western blot analysis

A patient with cutaneous vasculitis during infective endocarditis due to Lactobacillus casei was studied. Immune complexes (IC) were isolated from serum at the time of diagnosis and after 4 wk of therapy. Purification of IC used differential polyethylene glycol precipitation and competitive binding to staphylococcal protein A. In situ radioiodination of IC was performed, followed by SDS-polyacrylamide gel electrophoresis (PAGE). Anti-IC antisera were raised in rabbits by immunization with purified IC. IC were characterized by SDS-PAGE followed by electrophoretic transfer to nitrocellulose, incubation with antiserum and then with 125I protein A, and autoradiography. Although early and late IC differed quantitatively, there were no differentiating immunochemical features. Both IC contained a 60,000 dalton component that did not react with preimmune serum nor with anti-normal human serum. This component reacted with antiserum rendered specific for L. casei by affinity chromatography. The restricted antigen-antibody representation in IC contrasted with a wider panel of antibody activity in patient serum. The Western blot analysis proves to be an ideal method for the characterization of IC because of its sensitivity, dissociative capability, and preservation of immunoreactivity. IC isolated at a time removed from the original antigenic challenge may provide insight into the nature of the inciting antigen.

Characterization of sequential immune complexes in infective endocarditis by Western blot analysis

A patient with cutaneous vasculitis during infective endocarditis due to Lactobacillus casei was studied. Immune complexes (IC) were isolated from serum at the time of diagnosis and after 4 wk of therapy. Purification of IC used differential polyethylene glycol precipitation and competitive binding to staphylococcal protein A. In situ radioiodination of IC was performed, followed by SDS-polyacrylamide gel electrophoresis (PAGE). Anti-IC antisera were raised in rabbits by immunization with purified IC. IC were characterized by SDS-PAGE followed by electrophoretic transfer to nitrocellulose, incubation with antiserum and then with 125I protein A, and autoradiography. Although early and late IC differed quantitatively, there were no differentiating immunochemical features. Both IC contained a 60,000 dalton component that did not react with preimmune serum nor with anti-normal human serum. This component reacted with antiserum rendered specific for L. casei by affinity chromatography. The restricted antigen-antibody representation in IC contrasted with a wider panel of antibody activity in patient serum. The Western blot analysis proves to be an ideal method for the characterization of IC because of its sensitivity, dissociative capability, and preservation of immunoreactivity. IC isolated at a time removed from the original antigenic challenge may provide insight into the nature of the inciting antigen.

Clinical and microbial features of prosthetic joint infection

A one-year experience with prosthetic joint infection, in which 63 cases were identified, is reviewed. Thirty cases (48 percent) were early infections, in the first postoperative year, and 33 cases (52 percent) were late, occurring more than one year after implantation. Pain was the predominant symptom, but clinical clues suggesting infection were frequently absent, with fever in 43 percent and leukocytosis in only 10 percent. The radiographic appearance was more frequently abnormal in late infections (67 versus 37 percent, p less than 0.02). Staphylococci were predominant organisms, constituting 59 percent of prosthetic joint infections, and S. epidermidis was the predominant species in both early and later infections. Of the hematogenous infections, 11 of 13 occurred in the group with late infections; these were mostly nonstaphylococcal . Antigenic proteins of S. epidermidis were characterized by gel electrophoresis, but no infection-specific antigens could be identified when patient serum was compared with normal samples. Precipitating antibodies to the extracellular proteins of S. epidermidis were present in 50 percent of patients with S. epidermidis prosthetic joint infections, 27 percent of patients with nonstaphylococcal infections, 20 percent of patients with S. aureus infections, and 11 percent of normal subjects. In view of the increasing importance of prosthetic joint infection, further study of the pathogenesis of the infection and the host immune response is warranted.

Modulation of mononuclear phagocyte system function and circulating immune complexes by lyophilized concentrates in patients with classic hemophilia

Infusions of lyophilized antihemophilic factor concentrates in patients with hemophilia were found to affect both circulating immune complexes and in vivo mononuclear phagocyte system function. Following infusion nine patients had simultaneous assessment of serial immune complex levels and mononuclear phagocyte system clearance of IgG-sensitized autologous erythrocytes relative to a previously established baseline. Nine patients also had a separate second sequence, and two a third sequence, of serial immune complex measurements in relation to infusions. The net change in immune complexes over the 2- to 4-hr interval following infusion was consistent in 10 of 11 study pairs (P less than 0.01) despite different antihemophilic factor preparations for each study and different individual patient responses. This change could not be explained by immunochemical rearrangement in infusate and serum since in vitro mixing experiments showed no relationship to in vivo results. Change in mononuclear phagocyte system function showed a strong correlation with change in complexes (r = 0.70; P less than 0.05). It is suggested that infusions of antihemophilic factor can modulate the mononuclear phagocyte system which in turn alters immune complex levels. Both of these effects could potentially influence immune regulation which has been shown to be abnormal in other hemophiliac patient groups.

Serial circulating immune complexes and mononuclear phagocyte system function in infective endocarditis

Twenty patients with infective endocarditis were followed prospectively and all had elevated levels of circulating immune complexes (CICs) detected by staphylococcal binding assay. Mean CIC levels declined for the group as a whole (193 micrograms/ml +/- 24 to 100 +/- 17, p less than 0.05) and became undetectable in eight patients (47%) who were cured. Patients who died or had complicated courses had higher mean CIC levels at the start and finish (254 micrograms/ml +/- 24 and 145 +/- 37) of antibiotic therapy than patients with uncomplicated courses (178 micrograms/ml +/- 19 and 38 +/- 24), p less than 0.05. CIC levels did not decline significantly in patients with glomerulonephritis or arthritis, in contrast to patients without these features. Despite elevated CIC levels, 10 patients had enhanced mononuclear phagocyte system (MPS) function as assessed by Fc-dependent IgG-coated red blood cell clearance. These data suggest that CICs probably are pathogenic in endocarditis and may contribute to the development of arthritis and glomerulonephritis. Elevated CICs in infective endocarditis do not appear to be directly related to defective MPS function.

Induction of polymeric IgA rheumatoid factors in infective endocarditis

IgA and IgM rheumatoid factor activity, circulating immune complex levels, and antinuclear antibodies were measured in 17 patients with subacute or chronic infective endocarditis. Approximately three fourths of these patients had both IgA and IgM rheumatoid factors detectable by radioimmunoassay, and IgA and IgM rheumatoid factor activity was strongly correlated (p less than 0.01). In three patients studied, IgA rheumatoid factor activity was predominantly polymeric as assessed by sucrose density ultracentrifugation (55 to 92 percent of total rheumatoid factor activity) and could bind radiolabeled secretory component. No correlations between rheumatoid factor activity and circulating immune complex levels or antibodies to nuclear antigens were observed. These observations indicate that circulating polymeric IgA antibodies do not necessarily signify a mucosal stimulus for IgA production and also demonstrate differences in the intensity and spectrum of autoantibody production when compared with autoimmune diseases.

C1 inactivator-C1s complexes in inflammatory joint disease

A newly developed enzyme linked immunosorbent assay for the quantitation of C1 inhibitor (C1In)-C1s complexes was used to study activation of the classical pathway of complement in inflammatory joint diseases. Synovial fluid (SF) specimens were obtained from patients with rheumatoid arthritis (RA), other arthritides and non-inflammatory joint effusions. Paired serum (S) samples were obtained in 17 cases. Immune complexes (IC) were measured by the staphylococcal binding assay. C1In-C1s were higher in RA SF samples than in paired RAS samples (P less than 0.01). IC were higher in RA SF than non-RA SF. There was a significant inverse correlation between SF C1In-C1s complexes and SF total haemolytic complement. For all SF samples there was a correlation between IC and C1In-C1s complexes, but for RA SF alone there was no significant correlation between these parameters. There was no correlation between titre of rheumatoid factor and C1In-C1s complexes. These results demonstrate that activation of the classical pathway of complement is the hallmark of rheumatoid synovitis, yet also suggest functional heterogeneity of both circulating and intra-articular IC.

Intravenous gammaglobulin treatment of chronic idiopathic thrombocytopenic purpura

High-dose intravenous gammaglobulin (IVIgG) was given to 12 children and adults with chronic idiopathic thrombocytopenic purpura (ITP) to avoid splenectomy or because they either failed to respond to or required maintenance with high doses of steroids and/or immunosuppressives. The average platelet count increase to initial therapy was 239,500/microliters (range 23,000-790,000). A concomitant IgG Fc receptor blockade, measured by IgG-sensitized 51Cr-labeled autologous erythrocytes, was seen in 11 of 11 patients tested, both splenectomized and not splenectomized, lasting 3-4 wk. Six or more months after treatment, 2 children are in remission, 2 children and 2 adults are stable requiring no therapy with platelet counts of approximately 50,000 and 30,000, respectively, 3 children require maintenance IVIgG therapy at 2-10-wk intervals, and 1 child and 2 adults have become refractory to further IVIgG. Splenectomy was not performed in 4 children. Two adults were able to discontinue daily prednisone. The 3 patients who became unresponsive to Swiss Red Cross gamma-globulin (IgSRK) therapy did so in conjunction with a markedly elevated platelet-associated IgG and IgM. Serum IgM increased an average of 103 mg/dl after the IVIgG infusions. No significant side effects were seen.

Dynamics of mononuclear phagocyte system Fc receptor function in systemic lupus erythematosus. Relation to disease activity and circulating immune complexes

Seventeen pairs of longitudinal studies of mononuclear phagocyte system (MPS) Fc receptor function in 15 patients with systemic lupus were performed to explore the dynamic range of Fc receptor dysfunction in lupus and to establish the relationships between MPS function, clinical disease activity and circulating immune complexes (CIC). Fc receptor function was measured by the clearance of IgG sensitized autologous erythrocytes. At the time of first study the degree of MPS dysfunction was correlated with both clinical activity (P less than 0.05) and CIC (P less than 0.05). At follow-up patients with a change in clinical status show significantly larger changes in clearance function compared to clinically stable patients (206 min vs 7 min; P less than 0.001). MPS function changed concordantly with a change in clinical status in all cases (P = 0.002). Longitudinal assessments did not demonstrate concordance of changes in MPS function and CIC, measured by three different assays. The MPS Fc receptor defect in systemic lupus is dynamic and closely associated with disease activity. The lack of concordance of the defect with changes in CIC suggests that either CIC does not adequately reflect receptor site saturation or that other factors may also contribute to the magnitude of MPS dysfunction.

Systemic lupus erythematosus in men. Genetic and endocrine features

Sixteen men with systemic lupus erythematosus (SLE) were examined to assess their genetic and hormonal status. The results of buccal smears in 13 patients examined were normal. Hormonal profiling was done in eight patients receiving no steroid therapy. Four patients had elevated plasma estradiol levels (30, 35, 55, and 103 pg/mL; normal, 12 to 23 pg/mL) and elevated plasma estrone levels (115, 150, 155, and 160 pg/mL; normal, 48 to 100 pg/mL). One patient had a decreased serum testosterone level (134 ng/dL; normal, 300 to 1,000 ng/dL), with an elevated luteinizing hormone (LH) level (4.2 ng/mL; normal, 1.6 to 4.0 ng/mL). One patient had an elevation in both levels of serum follicle-stimulating hormone (17.6 ng/mL; normal, 1 to 5 ng/mL) and LH (10.0 ng/mL). Two patients given infusions of 3H-androstenedione and 14C-testosterone had normal findings from kinetic studies of these hormones. Hyperestrogenemia and hypoandrogenemia observed in some men with SLE suggest that female sex hormones may create an immunologic milieu that facilitates the autoimmune phenomena.

Defective Fc receptor-mediated function of the mononuclear phagocyte system in lupus nephritis

To determine whether patients with systemic lupus erythematosus and nephritis have more profound defects in mononuclear phagocyte system clearance than their counterparts without renal disease, we studed Fc receptor-mediated splenic clearance function in 32 patients. Clearance half-times were prolonged in patients with lupus erythematosus compared with those in normal controls (p less than 0.0001) and longer in patients with renal disease than in those without (p less than 0.025). Both renal (tau = 0.45, p less than 0.0002) and nonrenal (tau = 0.35, p less than 0.003) disease activity were significantly but independently associated with clearance half-times. When matched for nonrenal activity, patients with nephritis had greater clearance dysfunction than their counterparts without renal disease. Circulating immune complexes did not correlate with clearance for all patients. Neither B8 nor DR3 histocompatibility antigen markers differentiated the renal and nonrenal disease subgroups. The greater Fc receptor-mediated clearance dysfunction, which occurs in patients with lupus erythematosus and nephritis, could lead to enhanced glomerular deposition of immune complexes as a primary event, or as a secondary event amplifying previously established lesions.

Identification of bacterial antigens in circulating immune complexes of infective endocarditis

The presence of circulating immune complexes (IC) in patients with infective endocarditis has been well documented but the contributions of host and bacterial components to these IC have not been defined. To study this question, IC were isolated from serum of a patient with Streptococcus faecalis endocarditis by differential polyethylene glycol precipitation and competitive binding to staphylococcal protein A. A rabbit antiserum raised against the purified IC had reactivity by crossed immunoelectrophoresis primarily with an antigen derived from the cytoplasm of the infective organism. The antigen was a protein with a 12,000-dalton molecular mass. In situ radiolabeling of the IC bound to the protein A demonstrated a component of the same molecular mass as the bacterial antigen recognized by the antiserum. The patient serum had multiple antibody specificities reactive with bacterial antigens, including the antigen recognized by the rabbit anti-IC antiserum. These techniques for isolation and characterization of circulating IC may have value in the study of IC diseases in which the inciting antigens are not known.

Adult-onset Still's disease. Twenty-year followup and further studies of patients with active disease

Eleven female patients with adult-onset Still's disease were followed for 7-36 years (mean 20.2 years) after the onset of their illness. Ten of these patients had a chronic course characterized by remissions and exacerbations of arthritis associated with fever and rash. Five patients had terminal interphalangeal involvement, and carpal ankylosis was demonstrated on x-ray film in 10. Two patients developed a widespread polyarthritis, and renal amyloidosis was diagnosed 10 years after disease onset in the most severely affected patient. In 4 patients studied during an exacerbation of the disease, circulating immune complexes were detected by the staphylococcal A binding assay, but not by the C1q binding assay. Synovial fluid analysis in 1 patient revealed a low C3 level and total hemolytic complement (CH50) together with immune complexes and IgG rheumatoid factor. Immune complexes were not identified in the characteristic Still's rash by immunofluorescence or electron microscopy, although mast cell degranulation, neutrophil lysis, and perivascular fibrin deposition were reminiscent of immune complex--mediated vascular injury. The clinical and laboratory features as well as the long-term course of adult- and juvenile-onset systemic Still's disease are similar, but further studies of genetic markers and immunopathology are required to establish a common pathophysiology.