Rheumatoid factor in syphilis

Longitudinal rheumatoid factor autoantibody responses after SARS-CoV-2 vaccination or infection

Background

Rheumatoid factors (RFs) are autoantibodies that target the Fc region of IgG, and are found in patients with rheumatic diseases as well as in the healthy population. Many studies suggest that an immune trigger may (transiently) elicit RF responses. However, discrepancies between different studies make it difficult to determine if and to which degree RF reactivity can be triggered by vaccination or infection.

Objective

We quantitatively explored longitudinal RF responses after SARS-CoV-2 vaccination and infection in a well-defined, large cohort using a dual ELISA method that differentiates between true RF reactivity and background IgM reactivity. In addition, we reviewed existing literature on RF responses after vaccination and infection.

Methods

151 healthy participants and 30 RA patients were included to measure IgM-RF reactivity before and after SARS-CoV-2 vaccinations by ELISA. Additionally, IgM-RF responses after a SARS-CoV-2 breakthrough infection were studied in 51 healthy participants.

Results

Published prevalence studies in subjects after infection report up to 85% IgM-RF seropositivity. However, seroconversion studies (both infection and vaccination) report much lower incidences of 2-33%, with a trend of lower percentages observed in larger studies. In the current study, SARS-CoV-2 vaccination triggered low-level IgM-RF responses in 5.5% (8/151) of cases, of which 1.5% (2/151) with a level above 10 AU/mL. Breakthrough infection was accompanied by development of an IgM-RF response in 2% (1/51) of cases.

Conclusion

Our study indicates that de novo RF induction following vaccination or infection is an uncommon event, which does not lead to RF epitope spreading.

The Impact of Pediatric Rheumatic Diseases on Sexual Health, Family Planning, and Pregnancy

A comprehensive review of reproductive health subtopics, including sexual intercourse, romantic relationships, contraception, sexually transmitted infections, pregnancy, and infertility, as they pertain to patients with pediatric rheumatic diseases and those who care for them.

Serum rheumatoid factor is correlated with liver fibrosis in patients with chronic hepatitis B

BACKGROUND AND AIM

Non-invasive methods are being developed to evaluate liver fibrosis. In this study, we aimed to evaluate the diagnostic performance of rheumatoid factor (RF) to predict liver fibrosis in chronic hepatitis B (CHB).

METHODS

A total of 235 non-arthritic, treatment-naive patients with hepatitis B virus (HBV) were enrolled in this study. The RF level was analyzed concurrently with HBV-DNA and routine biochemical tests. The liver biopsies were scored by using the Knodell modified histology activity index (HAI) and the Ishak fibrosis score.

RESULTS

Mean age, ALT, AST, ALP, GGT, INR, and HBV-DNA levels were significantly higher, and mean albumin and platelet levels were significantly lower in the RF positive group than the RF negative group. Liver biopsy was performed in 112 (47.66%) patients, and the RF positivity rate was 18 (15.38%) in the infection subgroup and 73 (61.86%) in the hepatitis subgroup. Along with the RF positivity rate, the fibrosis and HAI scores were also increased. A high fibrosis score is associated with a high RF positivity rate.

CONCLUSIONS

In the current study, we found that there was a significant positive correlation between RF and liver fibrosis stage in patients with CHB. The RF that is easily obtained with low cost may be considered as an alternative biomarker for predicting liver fibrosis in CHB.

Proteomics analysis reveals differential pattern of widespread protein expression and novel role of histidine-rich glycoprotein and lipopolysaccharide-binding protein in rheumatoid arthritis

Rheumatoid factor (RF) is an auto-antibody against antigen-antibody immune complexes. RF is valuable as a biomarker for the screening of autoimmune and infectious diseases. However, it is suggested that RF would be a more powerful biomarker when used complementarily with RF-correlated proteins. In this study, we utilized a proteomic approach to analyze global protein expression in RF-low and RF-high subjects using high-performance liquid chromatography tandem mass spectrometry. Histidine-rich glycoprotein (HRG) and lipopolysaccharide-binding protein (LBP) were found to be differentially expressed between RF-low and RF-high subjects (cut-off > 2-fold, p < 0.05), which was validated by enzyme-linked immunosorbent assay. To evaluate whether both proteins allow discriminating rheumatoid arthritis patients from healthy controls, receiver-operating characteristic (ROC) curves were analyzed. Areas under the ROC curves of HRG and LBP were 0.861 and 0.888, respectively. The correlation between RF and HRG was statistically significant (p = 0.003), and LBP was also correlated with RF (p = 0.044), as indicated by correlation analysis. HRG and LBP are reportedly involved in RF-producing and RF-correlated diseases. Thus, we propose that HRG and LBP could be useful screening markers for RF-correlated diseases.

Rheumatoid factor revisited

PURPOSE OF REVIEW

Initial studies of the pathogenesis of rheumatoid arthritis focused on the role of rheumatoid factor and immune complex-associated vasculitis and synovitis. Subsequent work has delineated T cell responses, the role of cytokines, chemokines, and the aggressive nature of rheumatoid synovitis. Recent findings underscore the importance of humoral immunity in this entity and are the subject of this review.

RECENT FINDINGS

By the discovery of anti-cyclic citrullinated peptide, anti-RA33, and anti-GPI antibodies in the human and mouse systems, respectively, the impact of humoral autoimmunity in rheumatoid arthritis regained remarkable interest. This review summarizes recent insights into humoral autoimmunity in rheumatoid arthritis in the context of the generation of rheumatoid factors, including B cell activation via toll-like receptors and genetic predispositions that can trigger the induction of rheumatoid arthritis. The generation of rheumatoid factors that can also be found during host defense against infectious agents and under pathologic conditions, such as rheumatoid arthritis, Sjögren syndrome, and hepatitis C-associated mixed cryoglobulinemia after hepatitis C infection is likely the result of genetic predispositions and the intensity of the (primary) immune reaction. Models of the role of rheumatoid factors in health and disease, including related lymphomagenesis, will be discussed.

SUMMARY

In patients with rheumatoid arthritis, the induction of rheumatoid factors can be taken as an indicator of severe disease with a striking involvement of B cell activation. Very recent clinical trials using B cell depletion support the concept that humoral immunity, as evidenced by the production of rheumatoid factors, plays a significant role in the course of the disease.

Rheumatoid factors: host resistance or autoimmunity?

Rheumatoid factors (RFs), autoantibodies that bind to the Fc portion of IgG, are important in the immune response. RF-committed B-cells exist in the circulating lymphocyte pool in a high frequency (approximately 1-2 %) in normal individuals and in patients with pathological conditions associated with the sustained levels of circulating RF, such as rheumatoid arthritis (RA), Sjogren's syndrome (SS), and mixed cryoglobulinemia, associated with hepatitis C virus infection. RFs are induced by many infectious entities (viruses, bacteria, parasites) as a consequence of a secondary immune response to the pathogen, but usually the response is transient. It is likely that RFs play an important role in the host's defense against infection, both at the cellular level, where the RF B-cell can be an antigen presenting cell which can promote the antipathogen response, and at the humoral level, where RFs can contribute to the mopping up of the IgG antipathogen antibodies by contributing to immune complex formation and clearance. There has been much research on RFs in chronic pathological conditions, and the literature pertaining to their origin, structure, binding specificities, and possible roles in disease are discussed. The importance of the host defense, sometimes at the expense of an autoimmune response, is a balance that needs to be considered in light of a possible outcome of health or disease.

Immunoglobulin M capture assay for serologic confirmation of early Lyme disease: analysis of immune complexes with biotinylated Borrelia burgdorferi sonicate enhanced with flagellin peptide epitope

We previously reported on the efficacy of the enzyme-linked immunoglobulin M capture immune complex (IC) biotinylated antigen assay (EMIBA) for the seroconfirmation of early Lyme disease and active infection with Borrelia burgdorferi. In earlier work we identified non-cross-reacting epitopes of a number of B. burgdorferi proteins, including flagellin. We now report on an improvement in the performance of EMIBA with the addition of a biotinylated form of a synthetic non-cross-reacting immunodominant flagellin peptide to the biotinylated B. burgdorferi B31 sonicate antigen source with the avidin-biotinylated peroxidase complex detection system used in our recently developed indirect IgM-capture immune complex-based assay (EMIBA). As in our previous studies, the enzyme-linked immunosorbent assay (ELISA) reactivities of antibodies liberated from circulating ICs (by EMIBA) were compared with those of antibodies in unprocessed serum (antibodies found free in the serum, thus as an IgM-capture ELISA, but not EMIBA, because the antibodies were not liberated from ICs), the sample usually used in standard ELISAs and Western blot assays. The addition of the flagellin epitope enhanced the ELISA signal obtained with untreated sera from many Lyme disease patients but not from healthy controls. In tests with both free antibodies and ICs, with or without the addition of the flagellin epitope to the sonicate, we found the most advantageous combination was IC as the source of antibodies and sonicate plus the flagellin epitope as the antigen. In a blinded study of sera obtained from patients with early and later-phase Lyme disease, EMIBA with the enhanced antigenic preparation compared favorably with other serologic assays, especially for the confirmation of early disease.

IgM rheumatoid factor removal and performance of the FTA-ABS (IgM) test in congenital syphilis

OBJECTIVE

To determine the performance of the FTA-ABS (IgM) test in congenital syphilis after eliminating interference by IgM rheumatoid factor (RF) and preventing competitive inhibition by IgG.

DESIGN

The FTA-ABS (IgM) test was carried out before and after RF removal (achieved by immunoprecipitation of the IgG) in infants with congenital syphilis and controls.

SETTING

Newborns delivered in the Peninsula Maternal and Neonatal Services in Cape Town and infants presenting at Red Cross War Memorial Children's Hospital.

SUBJECTS

Infants with congenital syphilis aged 0-4 months were divided into those with clinical signs at presentation and those who were asymptomatic at delivery. In addition, patients without congenital syphilis but with similar clinical signs at presentation were investigated as were control infants.

OUTCOME MEASURE

The diagnosis of congenital syphilis was based on the criteria suggested by Kaufman et al (1977).

RESULTS

Amongst symptomatic infants with congenital syphilis the FTA-ABS (IgM) test was positive in 34 (92%) of 37 cases prior to abolishing the RF effect and in 29 (78.4%) of 37 cases afterwards (p = 0.19). In 12 cases of congenital syphilis who were asymptomatic at birth, 10 had positive FTA-ABS (IgM) tests before RF removal and only three had positive tests afterwards (p = 0.006). False positive tests were not found amongst 15 symptomatic infants whose clinical features mimicked those of the infants with congenital syphilis. Among 51 healthy infants the test had a false-positive rate of 2% in newborns and 13% in older infants. The false positive reactions were eradicated by IgG precipitation.

CONCLUSIONS

Following IgG and RF removal there was an improvement in the specificity of the FTA-ABS (IgM) test but this was at the expense of a loss of sensitivity, particularly in asymptomatic newborns. For newborns, if the FTA-ABS (IgM) test was positive, the patient was likely to require treatment for congenital syphilis, regardless of whether the result was due to the presence of RF or specific IgM.

Production of rheumatoid factor in adoptively immune guinea-pigs after challenge with Treponema pallidum

Guinea-pigs of inbred strains 2 and C4D were infused with various concentrations (1 x 10(8) to 4 x 10(8) of syngeneic nylon wool-purified Treponema pallidum-immune T lymphocytes (TPI-T) and challenged 24 hr later with virulent T. pallidum (10(8) organisms). The degree of protection depended on the number of infused T cells and was associated with an accelerated production of IgM rheumatoid factor (RF). Fully protected animals (4 x 10(8) TPI-T) did not produce treponemal antibodies or circulating immune complexes (CIC) but produced IgM RF detectable 10 days after infection. Partially protected animals (< or = 2 x 10(8) TPI-T) produced, 30 days post-infection, relatively low levels of treponemal antibodies but high levels of CIC and RF. Control animals infused with 2 x 10(8) TPI-T lymphocytes but not infected with T. pallidum, when monitored for a period of 6 weeks, did not produce treponemal antibodies, CIC, or RF, excluding the possibility that IgM RF could be generated by the donor's B cells contaminating (circa 3%) the TPI-T lymphocytes. Moreover, unprotected syngeneic control animals infused, prior to infection, with T. phagedenis biotype Reiter-immune T cells or with T. pallidum-free testicular inflammatory fluid-immune T cells responded with increasing levels of treponemal antibodies; only a few animals produced RF and CIC 5 months after infection similarly to control guinea-pigs infected only. The production of RF in partially protected animals responding to infection with treponemal antibodies and CIC was apparently associated with the presence of the CIC; but the mechanism of RF production in fully protected animals in which no antibodies or CIC were detected is currently unknown.

An analysis of false positive reactions occurring with the Captia Syph G EIA

AIM

The Captia Syph G enzyme immuno assay (EAI) offers the potential for the rapid automated detection of syphilis antibodies. This study was designed to assess the role of other sexually transmitted diseases (STDs) in producing false positive reactions in the Captia Syph G EIA. The role of rheumatoid factor (RF) as a potential source of false positives was also analysed.

METHODS

Patients who attended a genitourinary medicine (GUM) department and gave a false positive reaction with the EIA between 1988 and 1990 were compared with women undergoing antenatal testing and with the control clinic population (EIA negative) over the same time period. The incidence of sexually transmitted disease (STD) in the clinic population and the false positive reactors was measured in relation to gonorrhoea, chlamydia, genital warts, candidiasis, "other conditions not requiring treatment" and "other conditions requiring treatment." Male: female sex ratios were also compared. Ninety two RF positive sera were analysed with the EIA.

RESULTS

The rate of false positive reactions did not differ with respect to the diagnosis within the GUM clinic population. The antenatal group of women, however, had a lower incidence of false positive reactions than the GUM clinic group. No RF positive sera were positive on Captia Syph G EIA testing.

CONCLUSIONS

There is no cross reaction between Captia Syph G EIA and any specific STD or with RF positive sera. The lower incidence of false positive reactions in antenatal women is unexplained but may be related to physiological changes associated with pregnancy.

Improved immunoglobulin M serodiagnosis in Lyme borreliosis by using a mu-capture enzyme-linked immunosorbent assay with biotinylated Borrelia burgdorferi flagella

A mu-capture enzyme-linked immunosorbent assay (ELISA) for detection of serum immunoglobulin M (IgM) antibodies to Borrelia burgdorferi by using biotinylated purified B. burgdorferi flagella was developed. The diagnostic performance of the mu-capture ELISA was compared with that of a conventional indirect ELISA. Sera from untreated patients with erythema migrans (n = 50), neuroborreliosis (n = 100), and acrodermatitis chronica atrophicans (ACA; n = 48) were investigated. The cutoff of the ELISAs was adjusted to a diagnostic specificity of 98% on the basis of examination of 200 serum specimens from healthy controls. The mu-capture ELISA increased the diagnostic sensitivity in patients with erythema migrans from 32 to 48% (P less than 0.01) and in patients with neuroborreliosis from 37 to 57% (P less than 0.001). Because of an increased signal/noise ratio, the mu-capture ELISA yielded a significantly better quantitative discrimination of individual positive measurements from the cutoff (P less than 0.001). The increased signal/noise ratio was most likely a consequence of the elimination of IgG competition for the test antigen. This may also explain why 12% of patients with ACA showed significantly increased specific IgM levels only by the mu-capture ELISA. Of patients with ACA, 27% had IgM rheumatoid factor. The mu-capture principle with a directly labeled antigen showed no interference with IgM rheumatoid factor, in contrast to the indirect ELISA. The high diagnostic performance and ease of this three-step mu-capture ELISA make it suitable for routine anti-B. burgdorferi IgM serodiagnosis.

Evaluation of the Captia enzyme immunoassays for detection of immunoglobulins G and M to Treponema pallidum in syphilis

Two new enzyme-linked immunosorbent assays (ELISA), one for the measurement of immunoglobulin G (IgG) (Captia Syphilis-G) and one for the measurement of IgM (Captia Syphilis-M), were evaluated for detecting antibodies to Treponema pallidum. Serum samples from 169 patients, 96 with various stages of untreated syphilis, 63 with treated syphilis, and 10 who were noninfected, were investigated. All sera were also examined by traditional treponemal and cardiolipin tests and by the fluorescent treponemal antibody absorption (FTA-ABS) test for 19S(IgM). The overall sensitivity of Captia Syphilis-G was 98.3%. The IgG ELISA was very sensitive (100%) in all stages of untreated syphilis, except in primary syphilis (82%). In all diagnostic groups of syphilis, the reactivity of Captia Syphilis-M was similar to that of the 19S(IgM) FTA-ABS test, except in reinfections, in which the IgM capture ELISA was less sensitive. False-positive IgM capture ELISA results were not found in the 10 neonates born to mothers adequately treated for syphilis. However, of six serum samples containing rheumatoid factor, two were reactive in the Captia Syphilis-M test but not in the 19S(IgM) FTA-ABS test. This indicated that the specificity of the IgM capture ELISA was not absolute. All serum samples from treated patients were reactive in the IgG ELISA, but only 15 samples were reactive in the IgM capture ELISA, which appeared to be as effective as the 19S(IgM) FTA-ABS test in monitoring the effect of treatment. Simultaneous measurement of IgG and IgM antibodies for T. pallidum by the Captia immunoassays appears to be an efficient and simple method for confirming the diagnosis of syphilis as well as for indicating whether active disease is present.

Rheumatoid factor in congenital syphilis

The rheumatoid factor (RF) latex test was evaluated as a test for congenital syphilis. High risk newborns of mothers with untreated or inadequately treated syphilis were studied. The asymptomatic infants were followed up for between 3 and 4 months (or longer if the VDRL test was positive). The overall performance of the RF latex test was better than that of the other tests studied, even though the sensitivity was 46.7%. The specificity and positive predictive value of the test were 100% whilst the negative predictive value was 86.4%. The test was negative in all 84 controls studied. Although a negative RF latex test cannot be used to exclude congenital syphilis in an asymptomatic infant, a positive test in the presence of maternal syphilis should lead one to strongly suspect congenital syphilis.

Enzyme-linked immunosorbent assays for detection of immunoglobulin M to nontreponemal and treponemal antigens for the diagnosis of congenital syphilis

Sera from newborn infants born of mothers with a high risk of syphilis were examined for immunoglobulin M (IgM) antibodies in two different enzyme-linked immunosorbent assays (ELISAs), using either purified flagella from Treponema phagedenis biotype Reiter or the Venereal Disease Research Laboratory (VDRL) antigen as the antigen. All sera were also examined by the fluorescent treponemal antibody absorption (FTA-ABS) test for IgM. Three different groups of patients were studied. Group 1 consisted of 84 women and their newborn infants from a high-risk population for syphilis. Congenital syphilis was diagnosed in one child who had an IgM-positive cord blood specimen in both the ELISA and the FTA-ABS test. Group 2 consisted of 10 mothers and their newborn children. All mothers had positive syphilis-screening tests, and all children had signs of congenital syphilis. All but one child had positive IgM tests. Group 3 consisted of 15 mothers and their newborn children. These mothers had been treated for syphilis late in pregnancy, and all had a positive screening test at delivery. Two of the children had positive IgM tests, probably caused by reactivity after late intrauterine treatment of congenital syphilis. The specificities of the IgM tests were high when evaluated with sera from newborn children without signs of congenital syphilis. Even though IgM rheumatoid factor was found in all of the children tested with definite congenital syphilis, the rheumatoid factor did not cause false-positive results in either the VDRL ELISA or the flagellum ELISA. No significant IgG-IgM competition was noticed in the ELISAs. This study also confirmed that IgA antibodies do not cross the placenta; most newborn children with congenital syphilis were positive in the VDRL ELISA for IgA. Both the VDRL ELISA and the flagellum ELISA are very useful in the diagnosis of congenital syphilis and may be substitute for the FTA-ABS test. The VDRL ELISA for IgM will be especially useful in developing countries with a high incidence of congenital syphilis.

Laboratory aspects of Lyme borreliosis

Lyme borreliosis (Lyme disease), a common tick-borne disorder of people and domestic animals in North America and Europe, is caused by the spirochete Borrelia burgdorferi. Following the discovery and initial propagation of this agent in 1981 came revelations that other tick-associated infectious disorders are but different forms of Lyme borreliosis. A challenge for the clinician and microbiology laboratory is confirmation that a skin rash, a chronic meningitis, an episode of myocarditis, or an arthritic joint is the consequence of B. burgdorferi infection. The diagnosis of Lyme borreliosis may be established by (i) directly observing the spirochete in host fluid or tissue, (ii) recovering the etiologic spirochete from the patient in culture medium or indirectly through inoculation of laboratory animals, or (iii) carrying out serologic tests with the patient's serum or cerebrospinal fluid. The last method, while lacking in discriminatory power, is the most efficacious diagnostic assay for most laboratories at present.

Sensitivity and specificity of viral immunoglobulin M determination by indirect enzyme-linked immunosorbent assay

Four sources of error associated with virus-specific immunoglobulin M (IgM) determination by indirect enzyme-linked immunosorbent assay were recognized and analyzed. First, competitive inhibition due to specific IgG was demonstrated by experiments involving addition and subtraction of rubella-specific IgG. Second, the interference due to rheumatoid factors (RFs) of the IgM class (IgM-RFs) was studied thoroughly, and it appeared that the level of false positivity was more dependent on specific IgG titers than on IgM-RF titers. Third, it was found that some IgM-RFs, differing from conventional IgM-RFs in that they reacted only with isologous IgG, were responsible for further cases of false positivity. Fourth, the interference of an IgM reacting with some virus-unmasked cellular antigens was demonstrated for some uninfected individuals. All four interfering factors could be readily eliminated by simply premixing serum samples with a sheep anti-human gamma-chain serum. This single pretreatment was shown to eliminate false-negatives as well as false-positives in a further 2,004 sera tested for six viruses. These results also emphasize the frequency of RFs and their heterogeneity.

Rheumatoid factors in subacute bacterial endocarditis and other infectious diseases

Rheumatoid factors (RF) occur during the course of various infections such as leprosy, infective endocarditis, tuberculosis, trypanosomiasis, visceral larva migrans, infectious mononucleosis, influenza A, hepatitis A or cytomegalovirus. When first described it seemed logical to assume that host-self-immunization with autologous immune complexes provided the initial stimulus for RF production. Subsequently extensive characterization of bacterial, parasitic and viral Fc receptors has suggested an alternative explanation for rheumatoid factor associated with infections. It seems possible that patients make an initial immune response to infecting agent Fc receptors and that anti-anti-Fc receptors or anti-idiotypes either then directly stimulate rheumatoid factor production or are themselves rheumatoid factors. Such a hypothesis might also be applied to rheumatoid arthritis itself where either infecting agent or autologous cell Fc receptors could be the initial immunizing epitopes involved in rheumatoid factor production.

Detection of immunoglobulin M antibodies to Treponema pallidum in a modified enzyme-linked immunosorbent assay

The indirect enzyme-linked immunosorbent assay (ELISA) for detection of immunoglobulin M (IgM) antibodies to Treponema pallidum in sera of syphilitic patients is complicated by false positive reactions due to the interference of IgM rheumatoid factor (IgM-RF) activity and the presence of treponemal IgG antibodies. Another source of error producing false negative results is the competition between treponemal IgG and IgM antibodies for the binding sites on the antigen. To avoid these complications in the indirect Treponema pallidum-specific IgM-ELISA, total IgG was immunoprecipitated from sera of syphilitic patients prior to the assay. The IgM-RF from non-precipitated sera reacted in an IgM-RF-ELISA and in the Treponema pallidum-IgM-specific ELISA with identical titers. After precipitation of total IgG no reaction of the IgM-RF in the assay could be demonstrated. Competition between IgG and IgM antibodies can be prevented almost completely by the precipitation procedure. The sensitivity and specificity of the Treponema pallidum-specific IgM-ELISA after immunoprecipitation of total serum IgG were shown to be higher than 97 percent.