Distribution of rheumatoid factor activity in nonrheumatoid states

Effects of rheumatoid factor isotypes on disease activity and severity in patients with rheumatoid arthritis: a comparative study

The value of rheumatoid factor (RF) isotypes for assessing rheumatoid arthritis (RA) remains debatable. In this study, we have examined the relationships between RF isotypes and disease activity and severity in RA patients. Sixty-two patients with RA, 48 women and 14 men, were studied. RF was measured by nephelometry (RF-N) and IgG-, IgA-, and IgM-RF isotypes were measured using enzyme-linked immunosorbent assay. Serum C-reactive protein and erythrocyte sedimentation rate were also determined. The patients were classified according to disease activity, joint damage, functional status, and presence of pulmonary involvement, rheumatoid nodule, and secondary Sjögren's syndrome. Although the patients with active disease had significantly higher IgA-RF and IgM-RF levels compared to inactive patients, IgA-RF and IgM-RF were not found to be independently associated with disease activity in multivariate analysis. In patients with severe joint damage, IgA-RF and RF-N were significantly higher than those of the other patients. Multiple regression analysis showed that IgA-RF was the unique variable independently associated to severe joint damage. The patients with class III and IV functional index had significantly higher IgM-RF, IgA-RF, and RF-N levels compared to the patients with class I and II functional index; however, RFs were not significantly associated with functional status in multivariate analysis. IgA-RF and IgM-RF were significantly associated with pulmonary involvement and rheumatoid nodule, respectively. No significant associations were found between RF isotypes and secondary Sjögren's syndrome. Our results suggest that the clinical usefulness of IgA and IgM isotypes is better than RF-N. Elevated IgA-RF may be a marker of erosive disease. The usefulness of RF isotypes for monitoring disease activity or functional status appears to be limited.

Anti-cyclic citrullinated peptide autoantibodies measured by an automated enzyme immunoassay: Analytical performance and clinical correlations

BACKGROUND

Autoantibodies against cyclic citrullinated peptide (anti-CCP) are considered to be a sensitive and specific marker for rheumatoid arthritis (RA). This study evaluated the analytical performance and clinical correlation of an automated enzyme immunoassay (DSX, DINEX Technologies), for the detection of anti-CCP autoantibodies (DIASTAT anti-CCP, Axis-Shield, DUNDEE UK).

METHODS

Commercial controls and serum pools were used to determine its precision, analytical sensitivity, functional sensitivity and linearity. Sera from 83 patients with established RA and from 140 controls, including patients with various autoimmune diseases, viral infections and cancer, as well as sex- and age-matched healthy subjects, were studied. The rheumatoid factor (RF) was also assayed in each sample, and the results were compared to the anti-CCP findings.

RESULTS

The total imprecision (CV%) was 4.7-7.2% for concentrations ranging between 1.98 and 71.81 U/mL. The lower detection limit was 0.038 U/mL. At a cut-off of 5 U/mL, the sensitivity and specificity for RA were 67.5% and 99.3%, respectively. The RF had a sensitivity of 66.3% and a lower specificity 82.1% than anti-CCP. When the two antibodies were used together, the specificity was 99.1%.

CONCLUSIONS

The anti-CCP assay we examined on a fully automated system showed a good analytical performance (analytical and functional sensitivity, linearity) and good clinical correlation. We conclude that this system can provide rapid, useful data.

Membranoproliferative glomerulonephritis type II (dense deposit disease): an update

Membranoproliferative glomerulonephritis type II (MPGN II) is a rare disease characterized by the deposition of abnormal electron-dense material within the glomerular basement membrane of the kidney and often within Bruch's membrane in the eye. The diagnosis is made in most patients between the ages of 5 and 15 yr, and within 10 yr, approximately half progress to end-stage renal disease, occasionally with the late comorbidity of visual impairment. The pathophysiologic basis of MPGN II is associated with the uncontrolled systemic activation of the alternative pathway (AP) of the complement cascade. In most patients, loss of complement regulation is caused by C3 nephritic factor, an autoantibody directed against the C3 convertase of the AP, but in some patients, mutations in the factor H gene have been identified. For the latter patients, plasma replacement therapy prevents renal failure, but for the majority of patients, there is no proven effective treatment. The disease recurs in virtually all renal allografts, and a high percentage of these ultimately fail. The development of molecular diagnostic tools and new therapies directed at controlling the AP of the complement cascade either locally in the kidney or at the systemic level may lead to effective treatments for MPGN II.

Dimensions of antigen recognition and levels of immunological specificity

Although recognition and specificity are among the most fundamental concepts in immunology, there is a common tendency to equate these notions with the fit, especially in terms of molecular shape, between interacting molecules. Even in the case of monovalent recognition, there are factors that contribute to the energetics of the interaction that are not readily accounted for by detailed structural analysis of the interacting (epitopic and paratopic) molecular surfaces. Consequently, recognition involves more than just the three spatial dimensions and time. Factors such as solute-solvent interactions, molecular crowding, and confinement, not directly related to the details of the intermolecular interface, can play crucial roles in determining both intrinsic affinity and differential intrinsic affinity. Furthermore, stating that a given structural subunit (e.g., amino acid) is recognized in a given noncovalent interaction does not clarify whether the structural subunit in question participates in the interaction through van der Waals contact, contribution to intrinsic affinity, or differential contribution to relative intrinsic affinities for two or more different ligands. Additional factors become relevant in considering the specificity exhibited in multivalent interactions, cell activation, and activation of the whole immune system. Therefore, specificity as defined for a monovalent binding event can diverge from specificity as it is defined for higher-order interactions. A corollary of this conclusion is that the composition of epitopes and paratopes, defined in terms of the structural elements for which substitutions have an effect on the specificity-defining measurement, can differ in different contexts despite complete conservation of the structures that physically make direct contact. An analysis of specificity at the organismal level suggests that the immune system does not recognize or respond to substances that correspond precisely to either nonself substances or to dangerous substances. An alternative notion for the molecular origins of immunological discrimination does not require that there be any single reason for immune responsiveness. This concept of what the immune system recognizes and responds to derives from the recognition that the ultimate function of the immune system is to contribute to survival and reproductive success through any available means.

Erythema induratum and pulmonary tuberculosis

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Correlative studies of rheumatoid factors and anti-viral antibodies in patients with rheumatoid arthritis

An analysis of the relationship between the immune response to ubiquitous herpes family viruses, namely Epstein-Barr virus (EBV), cytomegalovirus (CMV), and varicella-zoster virus (VZV) and the presence of rheumatoid factors (RF), which are autoantibodies characteristic of patients with rheumatoid arthritis (RA), was conducted. Antibody profiles (RF, anti-viral antibodies) were monitored in the serum of the RA patients, and in normal individuals. No patient was found to have circulating RF in the absence of anti-viral antibodies. When the patients and normal controls were subdivided according to the presence of serum RF, it was found that when RF were present, the frequency of anti-CMV antibodies, but not anti-EBV or anti-VZV antibodies, was significantly higher (P = 0.02) when compared with RF-negative individuals. The titres of anti-CMV but not anti-VZV antibodies were found to increase in the RA patients with disease duration. To see if these viruses could stimulate RF production in vitro, peripheral blood mononuclear cells (PBMC) isolated from the patients and normal controls were stimulated with viral antigens. PBMC from normal controls, but not from RA patients, appeared to be responsive to viral antigen stimulation and produced RF. These data suggest that the immune response to CMV, to a greater extent than to EBV or VZV, correlates with the presence of RF.

Spontaneous in vitro production of rheumatoid factor during infectious exacerbations of cystic fibrosis: correlation with circulating immune complex levels

Rheumatoid factor (RF) production has been demonstrated during infections, including infectious exacerbations of cystic fibrosis (CF). The aim of this study was to evaluate the relationship of RF production to infection, and examine the mechanisms involved. Serial peripheral blood mononuclear cell (PBMC) cultures with measurement of spontaneous production of IgM RF, IgA RF, total IgM and IgA, and measurement of serum levels of immune complexes were carried out during exacerbations of CF. The percentage of B cells expressing CD5 was examined in a second cohort of acutely infected CF patients, and related to IgM RF production. IgM RF production was significantly elevated during acute infection compared with convalescence (P < 0.05), stable CF subjects (P < 0.005) and normal controls (P < 0.05). IgM RF production did not correlate with total IgM production in the majority of patients, but was closely related to circulating immune complex levels in 8/10 subjects. IgA RF production did not increase significantly during infection, and did not correlate with total IgA or IgM RF production, or with circulating immune complex levels. CD5+ B cells were not increased in the CF group, and the percentage of CD5+ B cells did not correlate with IgM RF synthesis. These observations suggest that RF production during infection is specifically induced, possibly by immune complex autoimmunization, and is not simply the result of polyclonal B cell activation. Different patterns of IgM RF and IgA RF synthesis suggest different mechanisms of induction.

Age-related interference with Chlamydia pneumoniae microimmunofluorescence serology due to circulating rheumatoid factor

Microimmunofluorescence (MIF) serology is commonly used in the diagnosis of chlamydial infections. In the MIF assay, Chlamydia pneumoniae elementary bodies were used to detect C. pneumoniae immunoglobulin G (IgG) and IgM antibodies in paired serum samples from 286 patients with respiratory illnesses. In 69 patients, MIF serology was compared with C. pneumoniae cultures. All C. pneumoniae cultures remained negative. However, 205 (71%) of 286 patients were C. pneumoniae antibody positive and 64 (22%) had MIF test results indicating recent infection; 11 showed a fourfold increase in IgG titer, 18 had IgG titers of greater than or equal to 1:512, and 41 had IgM titers of greater than or equal to 1:16. In 35 (55%) of 64 patients, a recent-infection diagnosis was based on C. pneumoniae IgM antibodies only. However, 78% of C. pneumoniae IgM-positive patients had circulating rheumatoid factor (RF) by rheumatoid arthritis latex assay. RF positivity increased with age. After absorption with anti-human IgG, all C. pneumoniae IgM-positive sera became C. pneumoniae IgM negative in the MIF assay. Twenty-five patients with active rheumatoid arthritis but without respiratory illness were also tested; 14 were C. pneumoniae IgG positive and C. pneumoniae IgM positive as well. Absorption of IgG from these RF-containing sera invariably resulted in disappearance of reactivity in the MIF IgM assay. We conclude that with age the serologic diagnosis of recent C. pneumoniae infection becomes increasingly prone to false-positive results unless sera are routinely absorbed prior to MIF IgM testing.

IgM rheumatoid factor in congenital syphilis: associations with clinical and laboratory findings

IgM rheumatoid factor (RF), measured by means of an ELISA, was detected in 92% of infants with congenital syphilis. Elevated levels were found to correlate with liver and renal involvement as well as the extent of the disease (P less than 0.05). In addition, levels of circulating immune complexes were closely related to the RF concentration (P less than 0.001). Following treatment of the infants both RF levels and VDRL titres declined at a similar rate (P less than 0.001). These findings indicated a close relationship between the disease process and IgM RF levels. It is postulated that IgM RF may add to immune complex deposition and exacerbate tissue damage in congenital syphilis.

IgM rheumatoid factor in cattle immunized against babesiosis

Polyclonal bovine IgM-rheumatoid factors (IgM-RFs) were examined in sera of cattle immunized against babesiosis. An enzyme-linked immunosorbent assay (ELISA) was used enabling rapid screening of serum samples. Results obtained indicate a rise of serum IgM-RF levels with age in healthy bovines. However when animals of similar age and pertaining to the same herd were examined, levels of serum IgM-RF exhibited a wide distribution range. Mean values in 60 sera of 2 yrs old clinically healthy heifers originating from a single herd were of 452.60 +/- 201.26 e.u. at 1 in 1,000 serum dilution and of 202.37 +/- 137.86 e.u. at 1 in 4,000 serum dilution. In a herd where repeated vaccination of dams against babesiosis was carried out 3 to 6 weeks before delivery either with live Babesia bovis parasites or soluble antigens of in vitro grown organisms, no significant differences in mean IgM-RF values were found between revaccinated animals and a control group. Nor did the mean values of serum IgM-RF of calves born to the respective groups of dams exhibit significant differences. It thus appears that immunization of healthy cattle against this parasite does not affect mean serum IgM-RF levels.

The latex test revisited. Rheumatoid factor testing in 8,287 rheumatic disease patients

Rheumatoid factor (RF) testing by latex fixation in 8,287 outpatients yielded a sensitivity of 81.6% and 78.0% at titers of 1:20 and 1:80, respectively, and a specificity against noninflammatory rheumatic disorders (NIRD) of 96.6% and 97.9% and against NIRD plus inflammatory disorders of 95.2% and 96.8%, respectively. The predictive value of a positive test result at the clinic prevalence rate for rheumatoid arthritis (RA) (16.4%) was approximately 80%, and was 70% at 10% prevalence and 10% at 1% prevalence. No associations of RF with age or sex were found in non-RA patients. RF titers increased minimally with age in RA patients and were higher in men than in women. This study suggests that latex testing is far more specific than has been believed and that the titer is not spuriously increased with age.

The presence of anti-protein A antibodies in patients with rheumatoid arthritis

Sixteen patients with rheumatoid arthritis (RA) were examined for the presence of anti-protein A antibodies. The F(ab')2 preparations from five RA patients showed significant binding to IgG-free protein A on ELISA. The protein A binding was further examined by immunoblotting. The F(ab')2 preparations of high protein A-binding protein gave a specific reaction with IgG-free protein A on nitrocellulose paper. This demonstrates the presence of anti-protein A antibodies in patients with RA. Those RA patients with anti-protein A antibodies had more active disease as judged by the Lansbury's activity index. The level of serum rheumatoid factor (RAHA) was significantly higher in patients with anti-protein A antibodies than in those without anti-protein A antibodies.

Epidemiological and genetic aspects of IgM rheumatoid factors

The occurrence of IgM rheumatoid factors (RF) was studied in a random sample of 8807 persons aged between 20 and 50 years in Tromsø, North Norway. Seropositivity for IgM RF was defined as a Waaler titre of 40 or more. A total prevalence of IgM RF of 1.36% was found, and a prevalence between 0.48-0.94% was found among the healthy persons, with no sex difference. Approximately 50% of IgM Rf positives are thus healthy. Only 11% of those with IgM RF suffered from rheumatoid arthritis. The majority of RF positive sera from healthy persons were low titred, and 81% of them converted to seronegativity in the course of 3.5 years. A low titred IgM RF appears rather harmless, while a high titre indicates a specific disease process. No association between IgM RF and DR4 could be found in healthy persons. The frequencies of Gm-allotypes a, b, e, f-n and x in healthy, RF positive individuals did not differ from the RF positive patients with RA, suggesting that the Gm-allotypes are not involved in the genetic pre-disposition for RA.

Evolution of the rheumatoid factor over time

With purpose to verify the epidemiological value of the Rheumatoid Factor's variations over time, we studied: 421 RA at first hospitalization (from 1976 to 1985; Group A); 348 consecutive RA with follow-up at 0, 6, 12, 24, and 48 months (Group B); 750 subjects, chosen at random from a healthy population, before and after 48 months (Group C). Five agglutination tests were used: three latex tests with human (2) and rabbit (1) IgGs; one red cells test on slide, and one in tube. The results were: uneven variations in positive results in all tests (Group A); the maximum confirmation of the basic profile are provide in short-term follow-up; in subsequent follow-ups, with the exclusion of the case of all the negative tests, the remaining profiles have a decreasing confirmation rate (Group B); the positive frequency is different in all the tests; this trend is sustained at follow-up (4 years later) in spite of the overall increase of positive results (Group C). Serum-positive RA, according to all or many tests, tend to reduce the number of positive results; healthy subjects (with few positive tests) tend to increase the number of positive results over time. RA with all the negative tests have a reasonably constant profile.

Environmental and social factors in rheumatoid factor epidemiology

The effect of social and environmental conditions on the epidemiology of Rheumatoid Factor (RF) in healthy population was studied. For this purpose 2 sample of 828 subject was studied using 5 tests for RF. Our sample included: 419 randomized subjects from a quarter at the outskirts of Bologna (high rate immigration, non homogeneous habits and health background; 409 randomized subjects from one rural small town on the Romagna's hills (no immigration, no change in residence or profession for generations, uniform, habits and health background). These tests included: three on slide with binded human (2) and rabbit (1) IgGs and sheep-cells tests-one on slide (Scat) and the other in tube (W.-Rose by Mizuoka). The most frequent positive test was Scat test, in urban population and one human IgG latex-test in the rural population. No urban subject reacted at the same time to 4 or 5 tests. Associated positive results for 2, 3 or 4 tests are usually observed in rural subjects. These results are the expression of the different and more uniform social and biological background acquired by rural people.

Development of rheumatoid factor research through 50 years

The discovery of Waaler in 1937 initiated fruitful research on RFs. It was not until the early 1960s that investigators in the field agreed that RFs are antibodies to Fc fragment of IgG. Separate factors combining with human and rabbit IgG and a factor combining with both these IgGs were at first demonstrated by mixed agglutination and then by separation through IgG-conjugated columns. Only RF combining with native autologous IgG should be considered an autoantibody. Other RFs are allo- or heteroantibodies. Cross-reacting RFs that combine with IgG of various species or with IgG and antigens of cell nuclei are of considerable interest. This cross-reactivity may be due to a combining site interacting with shared epitopes or otherwise to multispecificity of the RF molecule in that it has separate or partially overlapping combining sites acting on different epitopes. Experimental studies conducted since the mid-1950s showed that formation of RFs may be elicited by altered autologous IgG. Under natural conditions such alteration was shown to result from interaction of IgG antibody with its corresponding antigen and RF in many infectious diseases and possibly also in rheumatoid arthritis appeared to result from stimulation by immune complexes. More recently alterations of IgG by its reaction with microbial Fc receptors as well as non-specific polyclonal stimulation of B cells were shown to play a role in RF formation. RFs have been implemented in the pathogenicity of rheumatoid arthritis. Recent studies on dispersion of immune complexes in tissue sections by aggregated IgG showed that self-polymerization of IgG RFs results in formation of glomerular deposits in various nephropathies.

Metacarpophalangeal arthropathy associated with manual labor (Missouri metacarpal syndrome). Clinical radiographic, and pathologic characteristics of an unusual degeneration process

We describe 7 manual laborers with painful, palpably enlarged metacarpophalangeal joints. Characteristic radiographic changes were joint space loss, prominent osteophytes, and cystic metacarpal heads most prominent in the second and third metacarpophalangeal joints. In 3 of 4 patients, joint biopsy specimens showed subsynovial fibrosis and villous hyperplasia. All 7 patients had similar backgrounds of heavy work demanding sustained gripping motions of both hands, for periods that exceeded 30 years. We designated their condition metacarpophalangeal arthropathy associated with manual labor.

Non-Hodgkin's lymphoma of the synovium simulating rheumatoid arthritis

Skeletal involvement in patients with non-Hodgkin's lymphoma (NHL) is common, although direct involvement of the joints is unusual. We describe 2 adults who presented with features suggestive of a diagnosis of rheumatoid arthritis, but who were found to have diffuse NHL of the synovium. Results of a review of the literature, and assessment of the few similar cases in which NHL presented in the joint, suggest that the lymphoma may mimic either a monarticular or polyarticular synovitis, without lymphadenopathy or hepatosplenomegaly. Radiographic demonstration of associated bone destruction is the best evidence for non-Hodgkin's lymphomatous arthropathy in patients with rheumatic symptoms.

The musculoskeletal manifestations of cystic fibrosis

Twenty-seven patients with CF and joint complaints were reviewed. Twelve patients had arthritis, 11 had HPO, and four had symptoms of mechanical neck and back pain. We have confirmed the association of CF with an episodic form of arthritis. For the first time, we have reported that a subgroup of these patients later develop persistent synovitis with progressive asymmetric, erosive disease. The etiology of CF arthritis is unclear, but may relate to chronic infection and immune complex mechanisms. CF arthritis can be contrasted with CF induced HPO, which is associated with worse lung disease, a male predominance, and an older mean age of onset of symptoms. Mechanical neck and back pain may relate to an associated scoliosis or kyphosis in CF.

IgG rheumatoid factors and staphylococcal protein A bind to a common molecular site on IgG

The antigenic determinant on the Fc region of human IgG for two IgG rheumatoid factors (IgG-RF) from patients with rheumatoid arthritis were investigated in detail. The RF did not interact with IgG fragments that contained the C gamma 2 or C gamma 3 region alone, but required the presence of both regions for binding. The RF binding to solid-phase IgG were poorly inhibited by the IgG3 subclass and strongly inhibited by staphylococcal protein A (SPA) (42 kD), and fragment D of SPA (7 kD), indicating that the binding site is most likely the same as the Ga antigenic determinant described for IgM-RF, and is in the same location as the site on IgG that binds SPA. pH titration studies of the RF binding to IgG indicated the involvement of histidine and lysine or tyrosine side chains. Chemical modification studies showed the histidines were involved on the Fc side of the interactions, and tyrosines were involved on both the antigenic and antibody sides of the interactions. Lysines were not involved. The above information, and the knowledge of the number and position in space of the amino acid residues involved in the C gamma 2-C gamma 3 interface region of IgG, the binding site for SPA, and the amino acid substitutions in IgG3 that account for its inability to bind protein A, allowed the identification of the site on IgG that bind IgG-RF. This binding site involves some of the same amino acid side chains, His 435, Tyr 436, and one or both His 433 and 310, and is in the same location as the site that binds SPA. The same site is likely to be a common antigenic determinant for other RF. Furthermore, the described molecular mimicry suggests a biological relationship between bacterial Fc-binding proteins and the production of RF in rheumatoid arthritis.

Rheumatoid factor in syphilis

Immunoglobulin M (IgM) antibodies directed against IgG antibodies (rheumatoid factor [RF]) are known to occur often in patients with syphilis and to interfere with serological tests measuring specific antibodies of the IgM class. In this study we examined the occurrence and specificity of the RF and demonstrated a simple method to detect and eliminate the RF for a specific Treponema pallidum IgM enzyme-linked immunosorbent assay. We measured the occurrence of the RF with a sensitive enzyme-linked immunosorbent assay and found that it increased with the duration of syphilitic disease: 1 of 13 primary syphilis serum specimens, 3 of 13 secondary syphilis serum specimens, and 10 of 27 latent syphilis serum specimens were reactive in this RF test. Those sera containing IgM RF were immunoprecipitated with anti-human gamma chain antibodies and 2% polyethylene glycol until the RF was removed. One serum specimen from a patient in the secondary stage of syphilis and eight serum specimens from patients with latent disease still presented the RF after immunoprecipitation. Removal of the IgG antibodies also improved the sensitivity of the treponemal IgM test, indicating competition of these antibodies for binding sites of the antigen. The enzyme-linked immunosorbent assays for detection of RF and antitreponemal IgM antibodies are performed on the same plate. Theoretically, only sera positive for both tests have to be immunoprecipitated. But our findings indicated an increase in sensitivity of the IgM enzyme-linked immunosorbent assay after removal of IgG antibodies responsible for competition at the binding sites.

Rheumatoid factors in natural retrovirus infections of the cat and cattle

The occurrence of IgM-rheumatoid factors (RFs) was investigated in natural retrovirus infection of cats with feline leukaemia virus and of cattle with bovine leukaemia virus. IgM-RFs of polyclonal character were detected. No significant differences were observed between the amounts of IgM-RFs in the retrovirus-infected animals and their respective controls.

Antikeratin antibodies in serum and synovial fluid show specificity for rheumatoid arthritis in a study of connective tissue diseases

Tests for antikeratin antibodies (AKA) were performed on 2152 disease-associated and control sera by indirect immunofluorescence (IF) on rat oesophagus substrate. The incidence of AKA was significantly raised in rheumatoid arthritis (37%) in comparison with systemic sclerosis (8%), psoriasis (7%), ankylosing spondylitis (6%), systemic lupus erythematosus (3%), and normal controls (2%). AKA were detected in synovial fluid obtained from patients with rheumatoid arthritis (RA) (48%) but not from patients with other conditions. Further experiments on AKA-positive sera showed reactivity with stratum corneum of rabbit prepuce and lips. A specific rabbit antihuman keratin antiserum was shown, by IF and inhibition studies, to have a different specificity from that of spontaneous human AKA. AKA were associated with the presence of subcutaneous nodules in RA (p = 0.05), but not with Raynaud's phenomenon, Sjögren's syndrome, or HLA-DR4 positivity. Rheumatoid factor (RF) was not associated with AKA either in RA or in RF-positive disease controls.

Patterns of antihistone antibody specificity in systemic rheumatic disease. I Systemic lupus erythematosus, mixed connective tissue disease, primary sicca syndrome, and rheumatoid arthritis with vasculitis

A new fluorimetric assay was used to measure the relative amounts of antibodies to individual nuclear histones in sera from 102 patients with systemic lupus erythematosus (SLE), mixed connective tissue disease, primary sicca syndrome, and rheumatoid arthritis with vasculitis. In SLE sera, the predominant responses were to histones H-1, H-2B, and H-3, with marked elevations of binding to H-1 and H-2B in one-third of the patients, and to H-3 in one-fourth; antibodies of both the IgG and IgM classes were also detected. In a few SLE sera, the pattern of histone response differed or was restricted to 1 immunoglobulin class. In mixed connective tissue disease, only 2 of 9 sera showed elevated histone binding activity, the response being predominantly to H-3 in 1 patient and to H-1 and H-2B in the other. Binding to H-2B was also prominent in 2 of 3 patients with primary sicca syndrome. The highest antihistone reactivity and the most heterogeneous response patterns were observed in patients who had rheumatoid arthritis with vasculitis; 6 of 8 of those sera had elevated histone reactivity. In SLE, the highest histone binding results were found among patients with a history of photosensitivity. Histones are closely associated with DNA in the nucleosome, and we speculate that antihistone antibodies could arise as a result of damage to DNA, induced by drugs or irradiation.

The prevalence of HLA-DR4 and HLA-DR3 in healthy persons with rheumatoid factor

The frequency of the HLA antigen DR4 has been determined in healthy individuals with serum IgM RF. HLA DR4 was found in 11.6% of these persons as compared with 27% in healthy controls. Thus, no association between IgM RF and HLA-DR4 could be found in this material of healthy individuals. HLA-DR3 was found in 35% of healthy RF-positive persons, which was no different from the 30% prevalence among healthy controls. HLA-DR3 did not seem to be associated with high immune responsiveness of RF in RF-positive individuals.

A study of IgM rheumatoid factors in a middle-aged population of Northern Norway

A random selection of 8807 blood samples was analysed for the presence of IgM rheumatoid factor (RF). The sera were obtained from an epidemiological survey of rheumatoid arthritis in a middle-aged population of Northern-Norway. The prevalence of IgM-RF was 1.36% for the total population, but a prevalence of IgM RF in healthy individuals between 0.48-0.49% was found with no significant difference between males and females. The majority of RF positive sera were low titred. Only 11.4% of the persons possessing serum IgM RF suffered from classical or definite rheumatoid arthritis. Eighty-one per cent of the IgM RF positive individuals converted to seronegativity in the course of 3.5 years.

Microbial pathogenicity in oral soft tissue diseases

Recent work implicating microbial factors in the pathogenesis of several oral soft tissue diseases is discussed. These conditions include recurrent aphthous ulceration, oral cancer, Sjogren's syndrome, and the oral lesions of AIDS (the acquired immune deficiency syndrome). This paper reviews some recent work on these topics, with emphasis on investigations in our laboratory.

Rheumatoid factors in the sera of patient with gastrointestinal carcinoma

One hundred and nineteen patients with gastrointestinal (GI) malignancy (80 colorectal, 25 gastric and 14 pancreatic carcinoma) were studied for rheumatoid factors (RF), antinuclear antibodies (ANA) and immunoglobulin levels and the findings correlated with size of tumor, stage of disease and survival. Twenty three (19.3%) of the patients were RF seropositive compared to 5.7% of 70 matched controls (P = 0.02). In two thirds of the seropositive patients RF were detected prior to the initiation of treatment. The proportion of RF seropositivity increased significantly in patients with tumors larger than 4 cm and in patients with Stage D disease. The authors found a high incidence of ANA in the patients: 32.4% compared to 8% in normal subjects (P less than 0.01), but the proportion of RF in this group was not significantly different. Survival distributions of the RF positive cases were different from that of the other patients (18 versus 25 months median survival); however, this was not statistically significant. These findings indicate that RF in GI cancer patients sera is not rare and can be related mainly to "tumor load," although not considerably affecting survival.

Antibody to cytomegalovirus in patients with Sjögren's syndrome. As determined by an enzyme-linked immunosorbent assay

By use of enzyme-lined immunosorbent assay (ELISA), patients with Sjögren's syndrome were found to have levels of serum IgG antibody to cytomegalovirus twice those of matched control subjects, and IgM antibody levels which were three times as high. It may be relevant that features of cytomegalovirus infection are similar to those of Sjögren's syndrome.

Production of antibodies specific for Fc, Fab', and streptokinase-streptodornase in vitro by peripheral blood cells from patients with rheumatoid arthritis and normal donors. Identification of immune complexes in culture supernatants containing hidden antibodies reactive with Fab' fragments of immunoglobulin G

To study antibody (Ab) biosynthesis in rheumatoid arthritis (RA), the immunoglobulin (Ig)M anti-Fc, anti-Fab', and antistreptokinase-streptodornase (SKSD) produced by peripheral blood lymphocytes (PBL) were measured at intervals from 1 to 19 d in culture. PBL from 17 seropositive patients with active RA and 30 age-matched controls were evaluated. Within the first 24 h, PBL from six of eight patients released >30 ng IgM anti-Fc, even in the absence of pokeweed mitogen (PWM). This early release of Ab was blocked by cycloheximide. With or without PWM, PBL from normal donors did not release IgM anti-Fc until after 3-5 d in vitro. By day 9, unstimulated PBL from seven patients made > 100 ng IgM anti-Fc. Un-stimulated PBL from normals never made >95 ng of this Ab. When PWM was added, PBL from normal donors released as much IgM anti-Fc as was found in RA donor cultures. Paradoxically, addition of PWM to PBL of RA patients suppressed release of IgM anti-Fc in 4 of 17 cases to levels significantly below those found in unstimulated cultures of the same cells. Without PWM, PBL from RA donors frequently failed to make IgM anti-SKSD (P < 0.05 compared with normal donors' cells). With PWM, the quantities of IgM anti-SKSD released were comparable. Fluctuations in IgM anti-Fab' levels during the life-time of these cultures were sufficient to suggest that these Ab may be taken up in immune complexes. This hypothesis was verified by acidifying (pH 3.1) culture supernatants to which (125)I-Fab' had been added previously. The samples were then neutralized (pH 7.6) and 12% polyethylene glycol was added to separate free from antibody-bound (125)I-Fab'. This procedure increased the quantity of (125)I-Fab' precipitated by > 10-fold in some cases. These studies suggest that there are a variety of abnormalities in Ab biosynthesis in RA. These include spontaneous synthesis of comparatively large quantities of IgM anti-Fc, relatively suppressed release of IgM anti-SKSD, and a paradoxical reduction, in some cases, in the biosynthesis of IgM anti-Fc after addition of PWM.

Immunoglobulin E-rheumatoid factor in the serum of patients with rheumatoid arthritis, asthma, and other diseases

A solid-phase radioimmunoassay was developed to detect immunoglobulin (Ig)E antibodies that bound to human IgG. IgE-rheumatoid factor activity was found in the serum of 18 of 20 patients with seropositive rheumatoid arthritis, 1 of 4 patients with seronegative rheumatoid arthritis, 3 of 32 patients with seronegative rheumatoid arthritis, 3 of 32 patients with asthma, and in 1 patient with hypocomplementemic vasculitis and iodide sensitivity. Immunopathologic implications of IgE-rheumatoid factor are discussed.

Immunologic tests of value in diagnosis. 1. Acute phase reactants and autoantibodies

Acute phase reactants are nonspecific indicators of tissue necrosis and/or inflammation but may be helpful in determining activity of disease. Rheumatoid factor is likewise rather nonspecific, but its presence is helpful in predicting the course, severity, and complications of rheumatoid arthritis. Numerous antinuclear antibodies have been identified in collagen vascular diseases; perhaps the most specific association is between anti-Sm antibody and systemic lupus erythematosus. Anti-smooth-muscle and antimitochondrial antibodies can aid in differential diagnosis of liver disease, while antithyroid antibodies can perform a similar function in diffuse goiter. Anti-parietal-cell and anti-intrinsic-factor antibodies are quite specific for pernicious anemia.

Rheumatoid factor: correlation with recurrence in transitional cell carcinoma of the bladder

The serum rheumatoid factor was measured by the latex fixation test in different titrations in 100 cases of bladder tumors. The rheumatoid factor was found in transitional and squamous cell carcinoma of the bladder. The percentage of positive studies correlated well with the clinical staging of the tumors. The rheumatoid factor activity also correlated with the recurrence of transitional cell carcinoma. A high recurrence rate was found when the rheumatoid factor was present in contrast to a low recurrence rate when it was absent at the initial examination. The percentage of recurrences correlated with the titration of the rheumatoid factor. The mechanism of production of the rheumatoid factor and its correlation with tumor recurrence are discussed.

Immunological abnormalities in bronchiectasis with chronic bronchial suppuration

Fifty-three patients with bronchiectasis (chronic bronchial suppuration) of unknown cause, in whom the chronic production of purulent sputum was the prominent clinical feature, were investigated for possible immunological abnormalities. They were compared with two control groups comprising 50 patients with chronic bronchitis and emphysema and 33 patients with bronchial asthma. Forty-two patients with bronchiectasis(79%) had at least one abnormality of immunoglobulin, usually elevation of IgA, IgG or IgM. Eight patients had all three immunoglobulin levels raised and this was related to severity of disease. Similar increases in immunoglobulin levels were observed in the control groups, but the frequency and severity of these changes were significantly greater in the bronchiectasis patients. Two patients had IgA deficiency. There was a very high prevalence of rheumatoid factor (52%) and an increased prevalence of antinuclear factor (10%) in the bronchiectasis patients compared with the control groups. The presence of these autoantibodies did not correlate closely with severity of disease. Ten patients with bronchiectasis (19%) had one or more autoimmune disorders, and the association of severe bronchiectasis, Hashimoto's thyroiditis and pernicious anaemia in one patient is described in detail. The immunoglobulin changes, high incidence of autoantibodies and association with autoimmune disorders raises the possibility that in some patients with bronchiectasis (chronic bronchial suppuration) of apparent unknown cause abnormal immune mechanisms may be important in causing or perpetuating the condition.

The clinical and pathogenetic significance of rheumatoid factors

Rheumatoid factors are immunoglobulins with antibody specificity for antigenic sites on the Fc part of the heavy chain of IgG. The heterogeneity of RF in terms of antigenic specificity and class of immunoglobulin is indicative of the complexity of the provoking immune response. There is little doubt that in many patients rheumatoid factors are autoantibodies which form part of immune complexes, and that complexes containing IgG rheumatoid factor appear to be of pathogenetic importance. Although IgM rheumatoid factors are not specific for RA, their detection aids in the diagnosis and categorisation of rheumatoid arthritis. On the other hand, IgG rheumatoid factors occur in a variety of rheumatic diseases and are of little diagnostic value.

A comparison of three Mycoplasma synoviae rapid plate agglutination antigens in experimental M. synoviae infection in chickens

The course of experimental Mycoplasma synoviae and Mycoplasma galli-septicum infections was followed in groups of chickens to compare the specificity and sensitivity of three, commercially available, Mycoplasma synoviae rapid plate antigens and to determine the development of rheumatoid factor-like antiglobulins in their serum. All three antigens were adequate in sensitivity but one of them, which was found to contain 7% serum albumen, had better specificity in that it was not agglutinated by chicken antiglobulins prepared against either pig globulin or culture medium. Examination of the non-specific reactivity of M. synoviae antigen preparations containing different concentrations of pig globulin or 7% bovine albumen showed that the presence of 7% albumen or globulin suppressed the speed of non-specific reactions. Antiglobulin activity using globulin-coated latex was detected in the serum of chickens up to 62 weeks after foot pad inoculation with M. synoviae ; specific antibody, on the other hand, was still present when the experiment was terminated at 107 weeks post-inoculation. A serologically-positive M. synoviae infection in chickens produced by contact with birds infected via the respiratory tract did not stimulate antiglobulins detectable by the Latex test.

Lack of measurable complement fixing antibodies against viral antigens

A serological and clinical study was performed to find the common features of 130 patients without antibodies against 11 or more different antigens in the complement fixation (CF) test. These patients (=1.6%) were discovered during hte screening of 8,021 adult patients. Rheumatoid factor(s) (RF) were found in the sera of 113 of the patients. In the remaining 17 patients no common serological or clinical markers were found. Myeloma M-components were found in three cases. The lack of measurable CF antibodies in RF positive cases was apparently due to the inhibitory effect of RF(s) in the CF test. This was indicated by a positive reaction in CF after centrifugal separation of IgM and IgG fractions and also by the detection of antibodies using immunodiffusion method. Possible immune complexes were sought using the platelet aggregation test, which was positive for the sera of 47 (=37%) of the patients. The clinical diagnosis of the 130 CF-nonreactors was rheumatoid arthritis (RA) (ARA criteria) in 23 cases and pulmonary diseases in 65 cases. In a comparison group of equal size there were only 3 RA patients and 15 with pulmonary disease. RA was thus found in 20% of the RF positive CF-nonreacting patients. In the comparison group of 52 RA patients 8 CF-nonreactors were found (=15%). This suggests that the effect of RF(s) from RA patients in CF reaction varies greatly.

Hypertrophic osteoarthropathy and rheumatoid arthritis: simultaneous occurrence in association with diffuse interstitial fibrosis

A patient is described who was treated with high-dose prednisone in an attempt to halt progressive respiratory insufficiency associated with diffuse interstitial fibrosis. On cessation of steroid therapy the patient was noted to have radiologic manifestations of hypertrophic osteoarthropathy (HOA) as well as clinical and laboratory features of rheumatoid arthritis (RA). Subsequently a diffuse vasculitis developed with bowel perforation and sepsis leading to death.