Comparison of the presence of immune complexes in Felty's syndrome and rheumatoid arthritis

Felty syndrome: a case report

Background

Felty syndrome is a rare manifestation of chronic rheumatoid arthritis in which patients develop extraarticular features of hepatosplenomegaly and neutropenia. The typical presentation of Felty syndrome is in Caucasians, females, and patients with long-standing rheumatoid arthritis of 10 or more years. This case report presents a patient with an early-onset and atypical demographic for Felty syndrome.

Case presentation

Our patient is a 28-year-old African American woman with past medical history of rheumatoid arthritis diagnosed in 2017, asthma, pneumonia, anemia, and mild intellectual disability who was admitted to inpatient care with fever, chills, and right ear pain for 7 days. The patient’s mother, also her caregiver, brought the patient to the hospital after symptoms of fever and ear pain failed to improve. Our patient was diagnosed with sepsis secondary to pneumonia and urinary tract infection. She had been admitted twice in the past year, both times with a diagnosis of pneumonia. During this visit in September 2019, it was discovered that the patient had leukopenia and neutropenia. Bone marrow biopsy revealed increased immature mononuclear cells with left shift and rare mature neutrophils. During the hospital course, the patient was provisionally diagnosed with Felty syndrome and treated with adalimumab and hydroxychloroquine for her rheumatoid arthritis. Her sepsis secondary to pneumonia and urinary tract infection was treated with ceftriaxone and doxycycline, which was later switched to cefepime because of positive blood and urine cultures for Pseudomonas aeruginosa. She was discharged with stable vital signs and is continuing to control her rheumatoid arthritis with adalimumab.

Conclusion

This case report details the clinical course of sepsis secondary to pneumonia and urinary tract infection in the setting of Felty syndrome. Our patient does not fit the conventional profile for presentation given her race, age, and the length of time following diagnosis of rheumatoid arthritis.

Cells of the synovium in rheumatoid arthritis. Dendritic cells

Dendritic cells are the major antigen-presenting and antigen-priming cells of the immune system. We review the antigen-presenting and proinflammatory roles played by dendritic cells in the initiation of rheumatoid arthritis (RA) and atherosclerosis, which complicates RA. Various signals that promote the activation of NF-κB and the secretion of TNF and IL-1 drive the maturation of dendritic cells to prime self-specific responses, and drive the perpetuation of synovial inflammation. These signals may include genetic factors, infection, cigarette smoking, immunostimulatory DNA and oxidized low-density lipoprotein, with major involvement of autoantibodies. We propose that the pathogenesis of RA and atherosclerosis is intimately linked, with the vascular disease of RA driven by similar and simultaneous triggers to NF-κB.

Effect of circulating immune complexes on the binding of rheumatoid factor to histones

OBJECTIVE

To determine whether the reaction of rheumatoid factor (RF) with solid phase histone is due to the simultaneous presence of circulating immune complexes (CICs) or aggregated IgG.

METHODS

Serum samples from 56 patients with seropositive rheumatoid arthritis (RA) and 50 random blood bank donors were used. Binding of immunoglobulins to histone was determined by enzyme linked immunosorbent assay (ELISA) and by western blots. Aggregated IgG was obtained by heating at 61(o)C for 30 minutes.

RESULTS

Among the RA sera tested by ELISA, 54% were positive for histone binding by IgM, IgG, or IgA and 20% by IgM only. Heating of normal sera caused a significant enhancement in the binding of IgG to histone (p<0.001). This binding had a non-cognate behaviour-that is, it was destroyed by pepsin treatment of serum and was not significantly inhibited by competition with free histone. The same behaviour was seen for IgM, IgG, and IgA binding from RA sera. However, cognate IgG antibody binding to histone was inhibited by free histone and was resistant to pepsin digestion. Addition of heat aggregated IgG to RA sera or pretreatment of histone with aggregated IgG caused a significant increase in IgM binding to histone.

CONCLUSION

IgM, IgG, and IgA RF bind to solid phase histone as a result of attachment to histone of immune complexes or aggregated IgG and not as a result of a cognate reaction with histone.

Characterization of elevated neutrophil-associated IgG in various autoimmune disorders: not anti-neutrophil autoantibodies, but possibly immune complexes, bind to neutrophils

Neutropenia is frequently observed in a variety of autoimmune disorders. As the mechanism of neutropenia in these disorders, the destruction of neutrophils by anti-neutrophil autoantibodies has been believed since elevated levels of neutrophil-associated IgG (NAIgG) have been described. However, no data exists to characterize the nature of NAIgG and show NAIgG is an anti-neutrophil autoantibodies. We investigated whether the elevated NAIgG in these patients consists of anti-neutrophil autoantibodies. The NAIgGs of 91 patients with autoimmune disorders including 50 patients with idiopathic thrombocytopenic purpura, 13 patients with systemic lupus erythematosus, 11 patients with Hashimoto's thyroiditis and 10 patients with Graves' disease were analyzed. The level of NAIgG was high in 36 of 91 patients. Elution studies were performed to determine whether NAIgG has a nature of autoantibodies. In model experiments, the ether eluate from neutrophils sensitized with neutrophil-specific alloantibody (anti-NA2) reacted with donor neutrophils, whereas the eluates from those with model immune complexes (ICs) failed. These data indicated that the ether elution technique is useful to determine whether NAIgG consists of anti-neutrophil autoantibodies. The NAIgG on patient's neutrophils was eluted with ether and the reactivity of the eluate with normal neutrophils was investigated. The eluates from 34 of 36 patients with various autoimmune disorders with elevated NAIgG level failed to react with donor neutrophils. These data indicated that the elevated NAIgG in the majority of these patients did not consist of anti-neutrophil autoantibodies, but possibly of ICs.

Felty's and pseudo-Felty's syndromes

Felty's syndrome, consisting of rheumatoid arthritis, leukopenia, and splenomegaly, has been recognized as a distinct clinical entity for more than 60 years. Clinical and laboratory manifestations of the condition are reviewed. The major sources of morbidity and mortality remain recurrent local and systemic infections. Immunogenetic analysis shows a strong association with HLA-DR4, in addition to DQ beta 3b and C4B null allele. Potential mechanisms of neutropenia are contrasted, including impaired granulopoiesis and neutrophil-immune complex interactions. Lithium carbonate and splenectomy may have a role in the treatment of fulminant disease. Maintenance therapy should be directed at control of the underlying inflammatory arthropathy. A syndrome of proliferation of large granular lymphocytes and neutropenia, associated with rheumatoid arthritis in 23% to 39% of cases, has been described recently. Cases of "pseudo-Felty's" syndrome are often confused with traditional Felty's syndrome, which has twice the prevalence. The clinical and laboratory distinctions between these two conditions are elaborated.

Suppression of superoxide generation by normal polymorphonuclear leukocytes preincubated in plasma from patients with Felty's syndrome

Polymorphonuclear leukocytes (PMN) isolated from patients with Felty's syndrome (FS) generate fewer superoxide anions (O-2) upon stimulation with fmet-leu-phe than PMN from normal controls or patients with rheumatoid arthritis (RA). In this study, plasma samples were obtained from 12 patients with RA and 12 patients with FS. Incubation of normal PMN in plasma from Felty patients resulted in a significant reduction in both the rate and total quantity of O-2 generation when activated with fmet-leu-phe. This was not observed with plasma from RA patients. The capacity of a plasma sample to suppress O-2 generation correlated with plasma IgG-PMN-binding activity (IgG-PBA) and, to a lesser extent, with the content of circulating immune complexes (CIC). These data suggest that IgG-PBA and possibly CIC have a pathogenetic role in both qualitative and quantitative defects in PMN in Felty patients.

Depressed superoxide radical generation by neutrophils from patients with rheumatoid arthritis and neutropenia: correlation with neutrophil reactive IgG

Neutrophils of 31 patients with neutropenia and rheumatoid arthritis (RA) have been studied to assess their ability to generate superoxide radicals (O-2) on activation. Seventeen patients had classical Felty's syndrome and 14 presumed chrysotherapy related neutropenia. Results were compared with those from age and sex matched controls with uncomplicated RA and from normal subjects. Neutrophils from patients with Felty's syndrome had a significantly reduced ability to generate superoxide radicals when compared with the other three groups. In addition, serum levels of IgG polymorphonuclear leucocyte binding activity (IgG PBA) were also raised in the group with Felty's syndrome. A statistically significant inverse correlation existed between O-2 generation and IgG PBA. It is concluded that neutrophil reactive IgG may have an important role in both quantitative and qualitative defects in neutrophil function in Felty's syndrome.

Immune complexes and the pathogenesis of neutropenia in Felty's syndrome

The effect of the injection of serum from patients with rheumatoid arthritis (RA) and Felty's syndrome (FS) into mice on the number of circulating polymorphonuclear cells (PMN) was studied. The number of circulating PMN dropped to 61% (range 34-98%) of the initial counts after the injection of FS serum. This phenomenon was observed less frequently after injection of RA serum. In contrast, injection of serum from healthy controls always resulted in an immediate increase in the number of circulating PMN. No decrease in PMN counts was found after injection of FS sera pretreated with polyethylene glycol to precipitate immune complexes (IC). Gel filtration of FS sera on Sepharose 4B showed that the effect on the PMN counts in mice did not coincide with the 7S peak but occurred only in fractions containing larger material. Serum fractions from FS patients that contained IC were more active in producing neutropenia than the corresponding fractions from patients with RA. Microscopic and immunohistochemical examination of the organs from mice injected with FS serum showed sequestration of PMN and deposition of human IgG, IgA, and IgM in the vascular bed of the lungs. These results indicate that the interaction between PMN and IC of patients with FS leads to sequestration of PMN in mice and suggests that this interaction in humans may have a role in the pathogenesis of FS.

Comparison of five assays for immune complexes in the rheumatic diseases. An assessment of their validity for rheumatoid arthritis

Clinical assessment (disease activity, severity, and extraarticular manifestations) of 101 rheumatoid arthritis patients was correlated with several laboratory tests, including 5 immune complex assays: the bovine conglutinin, 125I-Clq binding, monoclonal rheumatoid factor inhibition, Raji cell, and staphylococci binding assays. Elevated disease activity indices were most closely associated with the presence of immune complexes detected by the 125I-Clq and staphylococci binding assays. There were significant but weak correlations between the level of disease activity and the level of immune complexes as measured by the bovine conglutinin, 125I-Clq binding, Raji cell, and staphylococci binding assays. Articular disease severity, as measured by anatomic stage, was discriminated by the bovine conglutinin, monoclonal rheumatoid factor inhibition, and staphylococci binding assays. Extraarticular manifestations were best discriminated by the Raji cell and staphylococci binding assays. We concluded that the sensitivity, specificity, predictive value, and overlap of the associations were not sufficient to warrant their wide use for the diagnosis and management of rheumatoid arthritis in individual patients. Conversely, the 125I-Clq and staphylococci binding assays were as good as the erythrocyte sedimentation rate and the IgG rheumatoid factor test (the 2 best of many examined) in assessing disease activity. Further prospective studies with these assays will determine their usefulness in following rheumatoid arthritis for a prolonged period.

Human neutrophil swelling induced by immune complexes and aggregated IgG

Using a Coulter counter method, the effects of various types of IgG-dependent phagocytic stimuli on human neutrophil (PMN) swelling were determined. Human heat aggregated IgG, ovalbumin-antiovalbumin (OV-anti-OV) immune complexes, and opsonized latex particles all induced PMN swelling. The OV-anti-OV immune complexes were effective, whether prepared at antigen-antibody equivalence (insoluble) or at 4 or 9 times antigen excess (soluble). Swelling of PMN occurred at 37 degrees C, but not at 4 degrees C. Complement was not present in any of the experiments. In contrast to the above results, native IgG, OV-anti-OV F(ab')2 immune complexes and unopsonized latex particles did not induce PMN swelling. These results suggest that the PMN swelling observed in this study is due to Fc-dependent, complement-independent membrane stimulation and/or phagocytosis.

Low molecular weight IgM in rheumatoid arthritis and other rheumatic diseases

Low molecular weight (LMW) IgM was measured in the serum and synovial fluid of patients with rheumatoid arthritis (RA) and other rheumatic diseases. High levels were seen in RA, particularly in rheumatoid vasculitis and Felty's syndrome, and significant correlations occurred between LMW IgM and the rheumatoid factor (RF) level and other indices that reflected active or severe disease. LMW IgM-RF, measured by radioimmunoassay in those column fractions containing LMW IgM, correlated significantly with LMW IgM (P less than 0.005); preliminary experiments suggested that in some sera, a considerable proportion of the LMW IgM consisted of LMW IgM-RF. We conclude that LMW IgM and LMW IgM-RF may have important implications in the immunopathogenesis of RA and other rheumatic diseases.

Neutrophil kinetics in Felty's syndrome

In 19 patients with Felty's syndrome, marrow production of neutrophils and neutrophil distribution were studied. Despite accelerated marrow release and disappearance of mature blood neutrophils, there was little or no increase in the marrow mitotic pool or in vitro progenitor cells. Only two patients had an increase in marrow neutrophils and precursors. Antineutrophil antibody was detected in seven of nine patients studied. Neither abnormal margination of blood neutrophils nor impaired marrow release of cells was detected. Skin exudate cellularity tended to correspond to prior history of infections, asymptomatic patients having more cellular exudates. Sustained neutrophil increments were observed in six of 10 patients following splenectomy, but in no patient did neutrophil kinetics return completely to normal. Three of four patients who failed to respond to splenectomy with sustained increments in blood neutrophils had a reduced mass of marrow neutrophils and neutrophil precursors when studied prior to splenectomy. No diminution in neutropenia was observed in any of five patients treated with lithium carbonate. This study indicates that multiple factors are involved in the pathogenesis of neutropenia in Felty's syndrome. In particular, neutropenia was associated with inadequate marrow granulocytopoiesis. The severity of the impairment, as determined by the mass of marrow neutrophils and precursor cells, may be useful in predicting response to splenectomy.

Cell mediated autoimmune granulocytopenia in a case of Felty's syndrome

A variety of mechanisms have been demonstrated or suggested to explain the neutropenia that accompanies Felty's syndrome. This case report presents with Felty's syndrome with recurrent infections with initially had a clinical response to splenectomy. Eleven years later profound neutropenia recurred. In-vitro evidence for cell mediated autosensitisation of peripheral blood lymphocytes to autologous bone marrow cells was found. The cellular abnormalities improved after high-dose corticosteroids but not lithium. However, there did not appear to be a reduction in the incidence of clinical infections. The finding suggests that granulocytopenia in some patients with Felty's syndrome may be an autoimmune phenomenon.

Serum-serum interactions in autoimmune mice

Sera from a majority of old, sick mice of the MRL/l strain interact with other MRL/l sera to form visible immunoprecipitates and fix complement. The mouse sera can be divided into two sets such that interset interactions are far more common than intraset ones. The reactive principle in each mouse serum is IgG in the form of an intermediate-sized complex. Reactivity between sera is dependent on IgG anti-IgG specificities.

The rarity of Felty's syndrome in blacks

Evidence is presented that Felty's syndrome (FS) is rare among black patients with rheumatoid arthritis (RA). All of 12 patients with FS seen at Parkland Memorial Hospital, Dallas, Texas betwen 1964 and 1978 were white. During this period 52% of patients admitted to the Parkland medical service were black and 31% of patients dischargd with a diagnosis of RA were black. The number of expected black cases of FS on the basis of the racial distribution of hospitalized patients with RA was 3.7 (P is less than 0.02 when the zero incidence in blacks was compared with the expected incidence). All 7 cases of FS observed at Charity Hospital, New Orleans, Louisiana between 1968 and 1978 were also white. During this period, 65% of patients discharged with a diagnosis of RA were black, and the number of expected black cases of FS was 4.5 (P is less than 0.001). These findings suggest a genetic basis for the development of leukopenia and splenomegaly in RA patients.

Increased C1q binding immune complexes in Felty's syndrome: comparison with uncomplicated rheumatoid arthritis

Sera from patients with Felty's syndrome (FS) and rheumatoid arthritis (RA) were examined for the presence of circulating immune complexes (IC) by using the 125I-C1q binding and monoclonal rheumatoid factor (mRF) techniques. Of 15 patients with FS, 9 (60%) had high 125I-C1q binding as compared to 3 of 26 RA patients (12%). The average C1q binding was significantly higher in the FS patients than in the RA patients without FS. C1q binding in both FS and RA patients was significantly higher than a group of 90 normal controls. In addition, serum C4 levels were significantly lower in the FS patients than in the RA patients. In contrast to these findings, IC levels in FS and RA patients were very similar when measured by the mRF technique. These studies indicate that FS patients have higher levels of complement-fixing IC in their sera than RA patients without FS. These findings raise the possibility that the complement-fixing IC found in these patients may play a role in the pathogenesis of neutropenia of FS.