Measurement of rheumatoid factors by an enzyme-linked immunosorbent assay (ELISA) and comparison with other methods.

Bampton, J. L. M.; Cawston, TE; Kyle, M V; Hazleman, B. L.

doi:10.1136/ard.44.1.13

Cited by 57 publications

(18 citation statements)

References 23 publications

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“…Without digestion, the specificity of IgG RF, and as a result of having all 3 isotypes correctly measured, is much lower 19,28,29 . This is likely due to nonspecific interaction between IgG on the solid phase and IgG in the patient's serum 5,6,10 . Thus, the clinician places a completely different emphasis on the RF test results for making the diagnosis if the isotype composition is known, which may be particularly valuable for early diagnosis or when the presentation is ambiguous, an aspect that deserves further support.…”

Section: Discussionmentioning

confidence: 99%

“…Thus, appropriate identification of RF+ patients in the screening process is essential. It has been shown that ELISA is significantly more sensitive than turbidimetry in detecting RF IgM 6 . Indeed, at the same level of specificity, 97%, we identified 282 RF+ specimens by ELISA and 218 by turbidimetry (Table 1).…”

Section: Rheumatologymentioning

confidence: 99%

“…The availability of IgG and IgA RF assays has significantly improved the diagnostic specificity of the test compared to latex agglutination and turbidimetry 5,6,7 . Moreover, the occurrence of RF IgA together with RF IgM was reported to precede the development of RA by several years 8,9 .…”

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confidence: 99%

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Relationship Between Rheumatoid Factor Isotypes and IgG Anti-Cyclic Citrullinated Peptide Antibodies

Jaskowski¹,

Hill²,

Russo³

et al. 2010

J Rheumatol

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Objective.To validate in a general patient population (GPP) the clinical value of measuring rheumatoid factor (RF) isotypes in relationship to IgG anti-cyclic citrullinated peptide (CCP) antibodies (CCP2 and CCP3).Methods.Serum samples were obtained as follows: 1021 GPP, for whom RF was ordered for diagnosis, 137 with rheumatoid arthritis (RA), 100 healthy blood donors (HBD), and 50 with systemic lupus erythematosus. Turbidimetry and ELISA were utilized for RF screening, and individual RF isotypes and IgG anti-CCP antibodies were measured by ELISA; RF IgG was measured after pepsin digestion.Results.We validated the generally accepted 90%–98% positive predictive value (PPV) and about 68% sensitivity of the anti-CCP2 test on our diagnosed cohorts as 96% (95% CI 89–99) and 65% (95% CI 56–73), respectively. The 282 RF IgM+ specimens identified in the GPP were subdivided into 3 subsets: (1) 83 as RF IgM+ IgG+ IgA+ with 63% (95% CI 51–73) anti-CCP2+ (i.e., sensitivity similar to the RA cohort); (2) 50 as RF IgM+ IgG− IgA+ with significantly fewer anti-CCP2+ (22%; 95% CI 12–36); and (3) about half as IgM+ IgG− IgA− with just 3% (95% CI 1–8) anti-CCP2+, i.e., not significantly different from the 1% (95% CI 0–5) in HBD. Thus, the chance for a specimen in the GPP to be anti-CCP2+ (i.e., to come from an RA patient) was increased by 7- and 21-fold, respectively, by identifying RF IgA and IgG in addition to IgM. About one-third of anti-CCP− RA patients in our cohort were RF IgM+ IgG+ IgA+, reflected as 3.4% in the anti-CCP2− GPP. The agreement between anti-CCP2 and anti-CCP3 was significantly higher for RF+ RA and GPP patients, 86% (95% CI 78–93) and 83% (95% CI 73–91), respectively, than for the RF− RA (27%; 95% CI 6–61), RF− GPP (4%; 95% CI 0–19), and non-RA controls. Anti-CCP2 but not anti-CCP3 significantly distinguished the HBD from the GPP (95% CI).Conclusion.Measurement of the 3 isotypes of RF may increase by 7- to 21-fold the chance of making the serologic diagnosis of RA; a testing algorithm is proposed. The anti-CCP antibody response appears significantly less peptide-specific in the presence of IgM RF than in its absence.

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Section: Discussionmentioning

confidence: 99%

Section: Rheumatologymentioning

confidence: 99%

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Relationship Between Rheumatoid Factor Isotypes and IgG Anti-Cyclic Citrullinated Peptide Antibodies

Jaskowski¹,

Hill²,

Russo³

et al. 2010

J Rheumatol

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“…Polystyrene plates (Maxisorb; Nunc, Rochester, NY) were coated with purified and heat-aggregated (631C for 20 min) human (IgM RF test) or rabbit IgG (IgA and IgG RF determinations) (40.0 mg/mL) in NaHCO 3 (0.05 mol/L, pH 9.6) according to previous studies (31)(32)(33)(34)(35), and quenched with 3% bovine serum albumin (BSA) fraction V in phosphate buffered saline-Tween 20 0.05% (PBS-T) (Sigma, St. Louis, MO). An appropriate dilution of serum samples was incubated in the antigencoated wells.…”

Section: Rf Immunoassaysmentioning

confidence: 99%

IgM, IgG, and IgA rheumatoid factors in pigeon hypersensitivity pneumonitis

Araiza¹,

León

Retana

et al. 2007

Clinical Laboratory Analysis

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The association of rheumatoid factor (RF) and lung disease in several immunologically mediated conditions has suggested that it may be physiopathologically relevant. Since previous reports in hypersensitivity pneumonitis (HP) have dealt mainly with the immunoglobulin M (IgM) RF measurement, we studied such antibody activity in other immunoglobulins, to determine the IgG and IgA RF levels in pigeon-HP, and in asymptomatic breeders (AB) and rheumatoid arthritis (RA) as controls. RFs were measured in 35 HP patients, 41 AB, 31 RA controls, and 55 healthy donors by enzyme-linked immunosorbent assay (ELISA) using human or rabbit immunoglobulin G (IgG), anti-IgM, F(ab')2 of IgG, and IgA F(ab')2 conjugates. An affinity chromatography, fragment crystallizable (Fc) preparations of IgG, pepsin digestion, and Western blots were used to confirm RF specificity. We also evaluated anti-avian antibodies (AA) and cross-reacting antibodies. The HP group revealed positive IgM (51.4%), IgG (31.4%), and immunoglobulin A (IgA) (34.2%) RF tests, and these antibody values exceeded the AB reference levels (P<0.02). HP and RA showed a similar frequency and distribution of RFs. Possible immunoassay interferences were excluded. As in other immunologically mediated diseases, IgG and IgA RFs may play a pathogenic role in HP, amplifying the inflammatory reaction, immune-complex formation, and complement activation. IgM-RF producing cells that have been implicated in the presentation of self and foreign antigens, and T-cell activation might induce the isotype switching of RFs.

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“…This procedure is based on the ELISA technique described in [14]. Briefly, 50 ~1 IgG (50 pg/ml in carbonate buffer at pH 9.6) was coated onto the wells of a 96-well immuno plate in quadruplicate and allowed to bind at 37°C for 1 h. Following 3 washes in PBS containing 0.05% Tween 20,0.5% SDS in PBS was added to each well to destroy any secondary and tertiary conformation (omission of this step, reduced lectin binding to N-acetylglucosamine by 75%, and to galactose by 25%).…”

Section: Modified Elba To Detect Terminal Carbohydrate Residuesmentioning

confidence: 99%

The effects of oxygen free radicals on the carbohydrate moiety of IgG

Griffiths

Lunec

1989

FEBS Letters

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The CH2‐linked glycoform of rheumatoid IgG is abnormal in having a reduced galactose content. This has been postulated to be a synthetic defect due to a decrease in the level of rheumatoid B cell galactosyltransferase. However, more recent work has indicated that agalactosylation may be common to chronic inflammatory diseases. In this work we have investigated the effect of oxygen free radicals (OFRs), which are generated by activated phagocytic cells at inflammatory sites, on the carbohydrate moiety of IgG. Radiolytically generated peroxy (ROO•) and hydroxyl radicals (OH•) but not superoxide anion radicals (O—2 −) were found to destroy galactose on IgG. After OH• attack, this was associated with an increase in the availability of N‐acetylglucosamine, possibly due to its presence as a terminal residue. These results suggest that the agalactosylation associated with chronic inflammation may not only be synthetic in nature, but may also be a consequence of post‐synthetic degradation by OFRs.

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Measurement of rheumatoid factors by an enzyme-linked immunosorbent assay (ELISA) and comparison with other methods.

Cited by 57 publications

References 23 publications

Relationship Between Rheumatoid Factor Isotypes and IgG Anti-Cyclic Citrullinated Peptide Antibodies

Relationship Between Rheumatoid Factor Isotypes and IgG Anti-Cyclic Citrullinated Peptide Antibodies

IgM, IgG, and IgA rheumatoid factors in pigeon hypersensitivity pneumonitis

The effects of oxygen free radicals on the carbohydrate moiety of IgG

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