Rheumatoid factor as an indicator of serum blocking activity and tumour recurrences in bladder tumours

Rheumatoid Factor: A Novel Determiner in Cancer History

Simple Summary

Rheumatoid factors are autoantibodies that characterize different autoimmune diseases, in particular rheumatoid arthritis, but that can also be found in the sera of the general healthy population. They have been mainly studied in the context of autoimmune diseases, but some evidence have suggested an association between their presence and the predisposition to develop cancer as well as a facilitation of cancer growth and progression in oncologic patients. In this review, for the first time we thus analyze and discuss the possible roles that these autoantibodies can assume in tumor history, from determiners of a heightened susceptibility of developing cancer to drivers of a reduced response to immunotherapies.

Abstract

The possible interplay between autoimmunity and cancer is a topic that still needs to be deeply explored. Rheumatoid factors are autoantibodies that are able to bind the constant regions (Fc) of immunoglobulins class G (IgGs). In physiological conditions, their production is a transient event aimed at contributing to the elimination of pathogens as well as limiting a redundant immune response by facilitating the clearance of antibodies and immune complexes. Their production can become persistent in case of different chronic infections or diseases, being for instance a fundamental marker for the diagnosis and prognosis of rheumatoid arthritis. Their presence is also associated with aging. Some studies highlighted how elevated levels of rheumatoid factors (RFs) in the blood of patients are correlated with an increased cancer risk, tumor recurrence, and load and with a reduced response to anti-tumor immunotherapies. In line with their physiological roles, RFs showed in different works the ability to impair in vitro anti-cancer immune responses and effector functions, suggesting their potential immunosuppressive activity in the context of tumor immunity. Thus, the aim of this review is to investigate the emerging role of RFs as determiners of cancer faith.

Anticitrullinated protein antibodies and rheumatoid factor are associated with increased mortality but with different causes of death in patients with rheumatoid arthritis: a longitudinal study in three European cohorts

OBJECTIVE

Patients with rheumatoid arthritis (RA)-related autoantibodies have an increased mortality rate. Different autoantibodies are frequently co-occurring and it is unclear which autoantibodies associate with increased mortality. In addition, association with different causes of death is thus far unexplored. Both questions were addressed in three early RA populations.

METHODS

2331 patients with early RA included in Better Anti-Rheumatic Farmaco-Therapy cohort (BARFOT) (n=805), Norfolk Arthritis Register (NOAR) (n=678) and Leiden Early Arthritis Clinic cohort (EAC) (n=848) were studied. The presence of anticitrullinated protein antibodies (ACPA), rheumatoid factor (RF) and anticarbamylated protein (anti-CarP) antibodies was studied in relation to all-cause and cause-specific mortality, obtained from national death registers. Cox proportional hazards regression models (adjusted for age, sex, smoking and inclusion year) were constructed per cohort; data were combined in inverse-weighted meta-analyses.

RESULTS

During 26 300 person-years of observation, 29% of BARFOT patients, 30% of NOAR and 18% of EAC patients died, corresponding to mortality rates of 24.9, 21.0 and 20.8 per 1000 person-years. The HR for all-cause mortality (95% CI) was 1.48 (1.22 to 1.79) for ACPA, 1.47 (1.22 to 1.78) for RF and 1.33 (1.11 to 1.60) for anti-CarP. When including all three antibodies in one model, RF was associated with all-cause mortality independent of other autoantibodies, HR 1.30 (1.04 to 1.63). When subsequently stratifying for death cause, ACPA positivity associated with increased cardiovascular death, HR 1.52 (1.04 to 2.21), and RF with increased neoplasm-related death, HR 1.64 (1.02 to 2.62), and respiratory disease-related death, HR 1.71 (1.01 to 2.88).

CONCLUSIONS

The presence of RF in patients with RA associates with an increased overall mortality rate. Cause-specific mortality rates differed between autoantibodies: ACPA associates with increased cardiovascular death and RF with death related to neoplasm and respiratory disease.

Lack of association of rheumatoid factor with either circulating immune complexes or tumor burden in cancer patients

The frequency of rheumatoid factor (RF) seropositivity and the frequency of association of RF with immune complex (IC) elevation were determined in 72 patients with a variety of solid tumors, in 78 patients with IC-associated diseases, 27 patients with non-IC-associated diseases, and in 31 normal healthy controls. The frequency of RF positivity in cancer patients (31%) was virtually identical to that in patients with IC-associated diseases (28%), and did not differ significantly from that seen in patients with non-IC-associated disease (15%). Whereas IC elevation was clearly related to tumor progress, RF was not. RF and IC status also appeared to be unrelated to each other, not only in cancer patients, but in patients with other diseases as well. The results do not support the concept that RF reflects progressive tumor growth or an immune response to IgG-containing immune complexes.

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.

Interference by rheumatoid factor and C1q in the detection of IgG complexes: studies of model systems by ELISA

Interference by purified IgM rheumatoid factors (RFs) and C1q in the detection of model complexes was studied by enzyme-linked immunosorbent assay (ELISA). Soluble monoclonal and polyclonal cryoglobulin IgM RFs and human or porcine C1q inhibited dose-dependently the binding of human IgG complexes to solid-phase IgM RF, C1q, and bovine conglutinin (Kg). The inhibition patterns of the Kg binding were dependent on the order of confrontation between the reactants. To achieve inhibition, C1q or RF had to be offered to the complexes before treatment with fresh normal human serum (NHS); complexes pretreated with fresh NHS (alexinated complexes) were resistant to inhibition. Heating at 56 degrees C or 63 degrees C, which destroyed the alexinating capacity of NHS, did not affect the Kg binding of alexinated complexes. On the basis of present and previous findings it is concluded that intrinsic C1q and RFs are likely to interfere with detection of circulating immune complexes (CICs) in C1q- or RF-binding assays; they are less likely to interfere with detection of CICs in Kg-binding assays. The problems associated with selective removal of intrinsic C1q and RFs are discussed.

Q fever in Finland: clinical, immunological and epidemiological findings

Clinical, immunological and epidemiological features of 14 human cases of Q fever diagnosed at Aurora Hospital are presented. All patients had an acute febrile disease and 9 (64%) had respiratory symptoms, 4 (29%) verified pneumonia, and 9 (64%) hepatitis, which in 4 biopsied cases proved to be granulomatous. Presence of circulating immune complexes was shown in 10/11 patients investigated by the platelet aggregation test (PAT) and the platelet iodinated protein A (PIPA) test. Q fever is not known to be endemic in the Nordic Countries. However, the causative agent, Coxiella burnetii, should tolerate our climate and there is a rich potential animal reservoir. All patients had visited some endemic area shortly before they were taken ill. In 3 cases the interval between arrival in Finland and the onset of symptoms was more than double the reported maximal incubation period, namely 69, 75 and 88 days. We suggest that these patients acquired the infection after their return to Finland from their clothing or from souvenirs. If so, Q fever could be acquired by this mechanism by persons who have never visited an area where the disease is endemic.

C3b binding immune complexes and immunoconglutinins in human sera. Detection by enzyme-linked immunosorbent assay (ELISA)

An enzyme-linked immunosorbent assay (ELISA) designed to measure autoantibodies against C3b (immunoconglutinins: IK) also detects immune complexes (IC). Solid phase C3b, in addition to binding IK of IgG, IgM and IgA classes, bound aggregated human IgG, IgA and aggregated immunologically purified anti-tetanus toxid antibodies as well as model complexes of tetanus toxoid-human anti-toxoid. Significant C3b binding IgG, IgM and IgA activities were seen in the sera of 20 SLE patients but not in sera from healthy blood donors. Ultracentrifugation analysis of two SLE sera revealed C3b binding IgG and IgA activities in both light (7S) and heavy (greater than or equal to 11S) fractions. This indicates simultaneous presence of IK and IC in these sera. On the basis of the known relationship between IK and IC formation we suggest that the solid phase C3b ELISA may be of value in evaluating immune reactions in patients.

Rheumatoid factor in melanoma patients: alterations of humoral tumor immunity in vitro

Rheumatoid factors (RF) were associated with alterations of antibody reactions to melanoma cells in vitro by two serologic assays. Removal of RF from melanoma patients' sera by absorption with Cohn's Fraction II coated latex particles enhanced seroreactivity in the Immune Adherence (IA) assay and diminished IgM detection by the Indirect Membrane Immunofluorescence (IMI) assay. The addition of serum with high titers of RF to these assay systems led to diminution of IA reactivity and enhancement of IgM detection by IMI. Since these factors are found in cancer patients' sera and can alter humoral immune reactions directed against antigens on the membranes of tumor cells, their presence should be recognized when performing assays with tumor target cells. RF may be of significance in the host-tumor relationship in vivo.

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.

Binding affinity of human autoantibodies: studies of cryoglobulin IgM rheumatoid factors and IgG autoantibodies to albumin

The binding affinity of cryoglobulin IgM rheumatoid factors (RF) for human IgG and of human IgG anti-albumin autoantibodies for HSA was measured by the molecular sieving technique. The binding affinities of the two autoantibodies were consistently low (10(4)-10(5) 1/M) as compared to the affinities of corresponding hyperimmune animal antibodies (10(6)-10(8) 1/M). The findings were discussed in relation to theories on human autoimmunity. The existence of strict autotolerance at the T cell level and of autoreactivity at the low affinity B cell level was considered to be best compatible with the findings of this study and with the major known facts of autoimmunity.

Rheumatoid factor in sera of dermatitis herpetiformis patients

Serum specimens from 44 patients with dermatitis herpetiformis (DH) and 42 control patients were analyzed with solid-phase radioimmunoassay (RIA) developed to detect IgG and IgM class antibodies against herpes simplex virus (HSV) envelope antigen. They were also tested with different tests to detect rheumatoid factor (RF) as well as serum antibodies to gastric parietal cells, glomerular basement membrane, smooth muscle, mitochondria and nuclei. Total serum IgG, IgM and IgA quantification was performed concurrently. IgM class antibodies reacting in HSV envelope antigen RIA were found in 47.8% of the DH patients, but in none of the controls. The age distribution of the IgM positive patients was in accordance with the appearance of RF, representing elderly persons. The presence of RF in serum specimens was confirmed by removing the IgM reactivity with heat aggregated human gamma globulin adsorption and in 13 patients with positive serological tests for RF. No correlation was found with the appearance of RF and duration or severity of the disease or with the detection of RF and serum total IgM concentration. In DH patients antibodies to gastric parietal cells were found in 6 and to smooth muscle in 1 of 32 specimens tested.

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.

Blocking effect of rheumatoid factor on the in vitro cytotoxicity of lymphoid cells from carcinoma patients

Human cryo-IgM rheumatoid factor (RF) preparations blocked the tumor-specific in vitro cytotoxicity of ovarian or bladder carcinoma patients' lymphoid cells in microcytotoxicity assays. The effect was mediated by pretreatment of the effector cells. Cryo-IgM RF free of detectable IgG blocked in a dilution-dependent manner, and immunosorbent purification of contaminating IgG from another preparation did not abrogate the blocking effect. Control IgM preparations lacking RF activity did not block the cytotoxicity, and normal human serum preincubation of the RF preparations rendered them inactive, indicating that the blocking effect was due to the anti-IgG activity of the RF.