Study of Flare Assessment in Systemic Lupus Erythematosus Based on Paper Patients

Objective

To determine the level of agreement of disease flare severity (distinguishing severe, moderate, and mild flare and persistent disease activity) in a large paper‐patient exercise involving 988 individual cases of systemic lupus erythematosus.

Methods

A total of 988 individual lupus case histories were assessed by 3 individual physicians. Complete agreement about the degree of flare (or persistent disease activity) was obtained in 451 cases (46%), and these provided the reference standard for the second part of the study. This component used 3 flare activity instruments (the British Isles Lupus Assessment Group [BILAG] 2004, Safety of Estrogens in Lupus Erythematosus National Assessment [SELENA] flare index [SFI] and the revised SELENA flare index [rSFI]). The 451 patient case histories were distributed to 18 pairs of physicians, carefully randomized in a manner designed to ensure a fair case mix and equal distribution of flare according to severity.

Results

The 3‐physician assessment of flare matched the level of flare using the 3 indices, with 67% for BILAG 2004, 72% for SFI, and 70% for rSFI. The corresponding weighted kappa coefficients for each instrument were 0.82, 0.59, and 0.74, respectively. We undertook a detailed analysis of the discrepant cases and several factors emerged, including a tendency to score moderate flares as severe and persistent activity as flare, especially when the SFI and rSFI instruments were used. Overscoring was also driven by scoring treatment change as flare, even if there were no new or worsening clinical features.

Conclusion

Given the complexity of assessing lupus flare, we were encouraged by the overall results reported. However, the problem of capturing lupus flare accurately is not completely solved.

Impaired brachial artery endothelium dependent flow mediated dilation in systemic lupus erythematosus: preliminary observations

Our objective was to compare brachial artery endothelium dependent and independent vasodilation in lupus patients and healthy females, by means of high-resolution noninvasive brachial artery ultrasound. Endothelially mediated vasodilation was estimated noninvasively by examination of brachial artery responses to postischemic reactive hyperemia and endothelial independent vasodilation from response to sublingual glycerlynitrate (GTN) using high-resolution external vascular ultrasound. Five patients with known coronary artery disease (CAD), five with subclinical CAD, five with no CAD and five control subjects were assessed. Endothelium dependent vasodilation was significantly blunted in lupus patients with CAD as compared with healthy female controls (0.11 versus 11.1%, P 1/4 0.018). Corresponding values for lupus patients with subclinical CAD and no CAD were 11 and 9.6%, respectively. For each subject, endothelium dependent vasodilation (EDV) was related to endothelium independent vasodilation (EIV) to adjust for varying vascular smooth muscle responses to GTN in individual subjects. This ratio was markedly depressed in lupus patients with CAD as compared with control subjects (0.12 versus 1.15). The corresponding EDV/EIV ratios for patients with subclinical CAD and no CAD were similar at 0.69 and 0.65, respectively. The conclusion was that flow mediated vasodilation in lupus patients with coronary artery disease is markedly depressed as compared to healthy subjects.

Long-term organ damage accrual and safety in patients with SLE treated with belimumab plus standard of care

Objective

To examine long-term organ damage and safety following treatment with belimumab plus standard of care (SoC) in patients with systemic lupus erythematosus (SLE).

Methods

Pooled data were examined from two ongoing open-label studies that enrolled patients who completed BLISS-52 or BLISS-76. Patients received belimumab every four weeks plus SoC. SLICC Damage Index (SDI) values were assessed every 48 weeks (study years) following belimumab initiation (baseline). The primary endpoint was change in SDI from baseline at study years 5–6. Incidences of adverse events (AEs) were reported for the entire study period.

Results

The modified intent-to-treat (MITT) population comprised 998 patients. At baseline, 940 (94.2%) were female, mean (SD) age was 38.7 (11.49) years, and disease duration was 6.7 (6.24) years. The mean (SD) SELENA-SLEDAI and SDI scores were 8.2 (4.18) and 0.7 (1.19), respectively; 411 (41.2%) patients had organ damage (SDI = 1: 235 (23.5%); SDI ≥ 2: 176 (17.6%)) prior to belimumab. A total of 427 (42.8%) patients withdrew overall; the most common reasons were patient request (16.8%) and AEs (8.5%).

The mean (SD) change in SDI was +0.2 (0.48) at study years 5–6 (n = 403); 343 (85.1%) patients had no change from baseline in SDI score (SDI +1: 46 (11.4%), SDI +2: 13 (3.2%), SDI +3: 1 (0.2%)). Of patients without organ damage at baseline, 211/241 (87.6%) had no change in SDI and the mean change (SD) in SDI was +0.2 (0.44). Of patients with organ damage at baseline, 132/162 (81.5%) had no change in SDI and the mean (SD) change in SDI was +0.2 (0.53). The probability of not having a worsening in SDI score was 0.88 (95% CI: 0.85, 0.91) and 0.75 (0.67, 0.81) in those without and with baseline damage, respectively (post hoc analysis).

Drug-related AEs were reported for 433 (43.4%) patients; infections/infestations (282, 28.3%) and gastrointestinal disorders (139, 13.9%) were the most common.

Conclusion

Patients with SLE treated with long-term belimumab plus SoC had a low incidence of organ damage accrual and no unexpected AEs. High-risk patients with pre-existing organ damage also had low accrual, suggesting a favorable effect on future damage development.

Autoantibodies in systemic lupus erythematosus: comparison of historical and current assessment of seropositivity

Systemic lupus erythematosus (SLE) is characterized by multiple autoantibodies and complement activation. Recent studies have suggested that anti-nuclear antibody (ANA) positivity may disappear over time in some SLE patients. Anti-double-stranded DNA (dsDNA) antibody titers and complement levels may vary with time and immunosuppressive treatment, while the behavior of anti-extractable nuclear antigen (ENA) over time is less well understood. This study sought to determine the correlation between historical autoantibody tests and current testing in patients with SLE. Three hundred and two SLE patients from the ACR Reclassification of SLE (AROSE) database with both historical and current laboratory data were selected for analysis. The historical laboratory data were compared with the current autoantibody tests done at the reference laboratory and tested for agreement using percent agreement and Kappa statistic. Serologic tests included ANA, anti-dsDNA, anti-Smith, anti-ribonucleoprotein (RNP), anti-Ro, anti-La, rheumatoid factor (RF), C3 and C4. Among those historically negative for immunologic markers, a current assessment of the markers by the reference laboratory generally yielded a low percentage of additional positives (3-13%). However, 6/11 (55%) of those historically negative for ANA were positive by the reference laboratory, and the reference laboratory test also identified 20% more patients with anti-RNP and 18% more with RF. Among those historically positive for immunologic markers, the reference laboratory results were generally positive on the same laboratory test (range 57% to 97%). However, among those with a history of low C3 or C4, the current reference laboratory results indicated low C3 or C4 a low percentage of the time (18% and 39%, respectively). ANA positivity remained positive over time, in contrast to previous studies. Anti-Ro, La, RNP, Smith and anti-dsDNA antibodies had substantial agreement over time, while complement had less agreement. This variation could partially be explained by variability of the historical assays, which were done by local laboratories over varying periods of time. Variation in the results for complement, however, is more likely to be explained by response to treatment. These findings deserve consideration in the context of diagnosis and enrolment in clinical trials.

International consensus for a definition of disease flare in lupus

The Lupus Foundation of America (LFA) convened an international working group to obtain a consensus definition of disease flare in lupus. With help from the Paediatric Rheumatology International Trials Organization (PRINTO), two web-based Delphi surveys of physicians were conducted. Subsequently, the LFA held a second consensus conference followed by a third Delphi survey to reach a community-wide agreement for flare definition. Sixty-nine of the 120 (57.5%) polled physicians responded to the first survey. Fifty-nine of the responses were available to draft 12 preliminary statements, which were circulated in the second survey. Eighty-seven of 118 (74%) physicians completed the second survey, with an agreement of 70% for 9/12 (75%) statements. During the second conference, three alternative flare definitions were consolidated and sent back to the international community. One hundred and sixteen of 146 (79.5%) responded, with agreement by 71/116 (61%) for the following definition: "A flare is a measurable increase in disease activity in one or more organ systems involving new or worse clinical signs and symptoms and/or laboratory measurements. It must be considered clinically significant by the assessor and usually there would be at least consideration of a change or an increase in treatment." The LFA proposes this definition for lupus flare on the basis of its high face validity.

Lack of association between the interferon-alpha signature and longitudinal changes in disease activity in systemic lupus erythematosus

OBJECTIVE

To study the longitudinal expression of interferon (IFN)-inducible genes in systemic lupus erythematosus (SLE) and determine their suitability as disease biomarkers.

METHODS

RNA was isolated from the peripheral blood of 94 patients with SLE and 11 controls and reverse transcribed into cDNA. The expression levels of five IFN-responsive genes (LY6E, OAS1, IFIT1, ISG15 and MX1) were determined by quantitative PCR, normalised to GAPDH and summed to generate a global IFN score. Patients were followed longitudinally for a period of 3-12 months, and the association between disease activity, as measured by the SLE disease activity index (SLEDAI-2K), and other clinical and laboratory variables was examined.

RESULTS

The expression of all five IFN-responsive genes was significantly higher in patients with SLE than in controls. The expression of LY6E, OAS1, IFIT1 and the global IFN score was associated with high disease activity. The global IFN score was also associated with active renal disease, a decreased C3, and the presence of anti-dsDNA or anti-RNA binding protein antibodies at a single point in time. However, there was a poor correlation between changes in this score and changes in disease activity, C3 or anti-dsDNA antibody levels in patients followed longitudinally. In most patients the levels of IFN-induced gene expression remained relatively stable over 3-12 months despite marked changes in disease activity. Nevertheless, in patients with low/moderate disease activity, those with high IFN scores had a more recent history of sustained high disease activity.

CONCLUSION

The findings indicate that IFN-induced gene expression has limited clinical utility as a biomarker of acute changes in disease activity.

The relationship between cancer and medication exposures in systemic lupus erythaematosus: a case-cohort study

OBJECTIVE

To examine if, in systemic lupus erythaematosus (SLE), exposure to immunosuppressive therapy (cyclophosphamide, azathioprine, methotrexate) increases cancer risk.

METHODS

A case-cohort study was performed within a multi-site international SLE cohort; subjects were linked to regional tumour registries to determine cancer cases occurring after entry into the cohort. We calculated the hazard ratio (HR) for cancer after exposure to an immunosuppressive drug, in models that controlled for other medications (anti-malarial drugs, systemic glucocorticoids, non-steroidal anti-inflammatory drugs (NSAIDs), aspirin), smoking, age, sex, race/ethnicity, geographic location, calendar year, SLE duration, and lupus damage scores. In the primary analyses, exposures were treated categorically (ever/never) and as time-dependent.

RESULTS

Results are presented from 246 cancer cases and 538 controls without cancer. The adjusted HR for overall cancer risk after any immunosuppressive drug was 0.82 (95% CI 0.50-1.36). Age > or = 65, and the presence of non-malignancy damage were associated with overall cancer risk. For lung cancer (n = 35 cases), smoking was also a prominent risk factor. When looking at haematological cancers specifically (n = 46 cases), there was a suggestion of an increased risk after immunosuppressive drug exposures, particularly when these were lagged by a period of 5 years (adjusted HR 2.29, 95% CI 1.02-5.15).

CONCLUSIONS

In our SLE sample, age > or = 65, damage, and tobacco exposure were associated with cancer risk. Though immunosuppressive therapy may not be the principal driving factor for overall cancer risk, it may contribute to an increased risk of haematological malignancies. Future studies are in progress to evaluate independent influence of medication exposures and disease activity on risk of malignancy.

The role of non-corticosteroid related factors in osteonecrosis (ON) in systemic lupus erythematosus: a nested case-control study of inception patients

Several factors have been associated with the development of osteonecrosis (ON) in SLE but corticosteroid (CS) therapy has been the most consistent association. We sought to determine factors that predisposed to, or protected from, the development of ON in lupus patients when cumulative oral corticosteroid doses were matched between cases and controls, thereby removing presence of corticosteroid therapy and cumulative dose as risk factors. A nested case-control study of an inception cohort of SLE patients was used to determine the clinical, laboratory and therapeutic differences between patients who developed their first ON event and patients who did not develop ON, having matched these groups for their cumulative oral corticosteroid doses. Of the 570 patients seen within the first year after diagnosis 65 (11.4%) developed ON. None of the variables examined were found to confer additional ON risk in multivariate analysis. It appears that the major factor associated with the development of ON is corticosteroid therapy. Factors which may protect a majority of patients on corticosteroids from developing ON remain to be elucidated.

Mortality related to cerebrovascular disease in systemic lupus erythematosus

The objective of this study was to examine mortality rates related to cerebrovascular disease in systemic lupus erythematosus (SLE) compared to the general population. Our sample was a multisite Canadian SLE cohort (10 centres, n = 2688 patients). Deaths due to cerebrovascular disease were ascertained by vital statistics registry linkage using ICD diagnostic codes. Standardized mortality ratio (SMR, ratio of deaths observed to expected) estimates were calculated. The total SMR for death due to cerebrovascular disease was 2.0 (95% confidence interval [CI] 1.0, 3.7). When considering specific types of events, the category with the greatest increased risk was that of ill-defined cerebrovascular events (SMR 44.9 95% CI 9.3, 131.3) and other cerebrovascular disease (SMR 8.4, 95% CI 2.3, 21.6). Deaths due to cerebral infarctions appeared to be less common than hemorrhages and other types of cerebrovascular events. Our data suggest an increase in mortality related to cerebrovascular disease in SLE patients compared to the general population. The large increase in ill-defined cerebrovascular events may represent cases of cerebral vasculitis or other rare forms of nervous system disease; alternately, it may reflect diagnostic uncertainty regarding the etiology of some clinical presentations in SLE patients. The suggestion that more deaths are attributed to cerebral hemorrhage, as opposed to infarction, indicates that inherent or iatrogenic factors (eg, thrombocytopenia or anticoagulation) may be important. In view of the paucity of large-scale studies of mortality attributed to neuropsychiatric outcomes in SLE, our findings highlight the need for additional research in large SLE cohorts.

Lung cancer in systemic lupus erythematosus

BACKGROUND

Evidence points to a link between systemic lupus erythematosus (SLE) and an increased risk of lung cancer. Our objective was to provide a brief report of the lung cancer cases from an SLE cohort, with respect to demographics, histology, and exposures to smoking and immunosuppressive medications.

METHODS

Data were obtained from a multi-site international cohort study of over 9500 SLE patients from 23 centres. Cancer cases were ascertained through linkage with regional tumor registries.

RESULTS

We analyzed information on histology subtype for 30 lung cancer cases that had occurred across five countries. Most (75%) of these 30 cases were female, with a median age of 61 (range 27-91) years. In eight cases, the histological type was not specified. In the remainder, the most common histological type reported was adenocarcinoma (N=8; two of the adenocarcinomas were bronchoalveolar carcinoma) followed by small cell carcinoma (N=6), and squamous cell carcinoma (N=6) with one case each of large cell carcinoma and carcinoid tumor. Most (71%) of the lung cancer cases were smokers; only the minority (20%) had been previously exposed to immunosuppressive agents.

CONCLUSIONS

The histological distribution of the lung cancers from the SLE sample appeared similar to that of lung cancer patients in the general population, though the possibility of a higher proportion of more uncommon tumors (such as bronchoalveolar and carcinoid) cannot be excluded. A large proportion of the cancer cases were smokers, which is also not surprising. However, only a minority appeared to have been exposed to immunosuppressive agents. A large case-cohort study currently in progress should help shed light on the relative importance of these exposures in lung cancer risk for SLE patients.

Anti-dsDNA and anti-Sm antibodies do not predict damage in systemic lupus erythematosus

We aimed to determine whether anti-dsDNA and anti-Sm antibodies predict damage in systemic lupus erythematosus (SLE). Five-hundred inception patients from the University of Toronto Lupus Clinic were studied. Predictors assessed for the entire study period were: (1) raised anti-dsDNA on two consecutive occasions; (2) anti-dsDNA levels (normal, mildly or highly elevated); (3) presence of antiSm on any occasion. To account for disease duration, the following were assessed at three years post-inception: raised anti-dsDNA on two consecutive occasions; anti-dsDNA levels. These predictors were correlated with the following outcomes: (1) overall SLICC/ACR Damage Index (SDI) at the end of the study period; (2) frequency of damage in the cardiovascular, neuropsychiatric, musculoskeletal and renal components of SDI; ((3) SDI at five years for the predictors assessed at three years post-inception. In the multivariate analysis, presence of anti-DNA antibodies or of anti-SM were non-significant but sex, age at SLE diagnosis, disease duration, corticosteroid use and cumulative dose were strong predictors of damage. Raised anti-dsDNA on two occasions or anti-dsDNA levels in the three years post-inception patients did not predict damage at five years. The presence and levels of anti-dsDNA and anti-Sm antibodies do not predict damage in SLE.

Mortality in systemic lupus erythematosus

OBJECTIVE

To examine mortality rates in the largest systemic lupus erythematosus (SLE) cohort ever assembled.

METHODS

Our sample was a multisite international SLE cohort (23 centers, 9,547 patients). Deaths were ascertained by vital statistics registry linkage. Standardized mortality ratio (SMR; ratio of deaths observed to deaths expected) estimates were calculated for all deaths and by cause. The effects of sex, age, SLE duration, race, and calendar-year periods were determined.

RESULTS

The overall SMR was 2.4 (95% confidence interval 2.3-2.5). Particularly high mortality was seen for circulatory disease, infections, renal disease, non-Hodgkin's lymphoma, and lung cancer. The highest SMR estimates were seen in patient groups characterized by female sex, younger age, SLE duration <1 year, or black/African American race. There was a dramatic decrease in total SMR estimates across calendar-year periods, which was demonstrable for specific causes including death due to infections and death due to renal disorders. However, the SMR due to circulatory diseases tended to increase slightly from the 1970s to the year 2001.

CONCLUSION

Our data from a very large multicenter international cohort emphasize what has been demonstrated previously in smaller samples. These results highlight the increased mortality rate in SLE patients compared with the general population, and they suggest particular risk associated with female sex, younger age, shorter SLE duration, and black/African American race. The risk for certain types of deaths, primarily related to lupus activity (such as renal disease), has decreased over time, while the risk for deaths due to circulatory disease does not appear to have diminished.

Non-Hodgkin's lymphoma in systemic lupus erythematosus

BACKGROUND

Recent evidence supports an association between systemic lupus erythematosus (SLE) and non-Hodgkin's lymphoma (NHL).

OBJECTIVES

To describe demographic factors, subtypes, and survival of patients with SLE who develop NHL.

METHODS

A multi-site cohort of 9547 subjects with definite SLE was assembled. Subjects at each centre were linked to regional tumour registries to determine cancer cases occurring after SLE diagnosis. For the NHL cases ascertained, descriptive statistics were calculated, and NHL subtype frequency and median survival time of patients determined.

RESULTS

42 cases of NHL occurred in the patients with SLE during the 76,948 patient-years of observation. The median age of patients at NHL diagnosis was 57 years. Thirty six (86%) of the 42 patients developing NHL were women, reflecting the female predominance of the cohort. In the patients, aggressive histological subtypes appeared to predominate, with the most commonly identified NHL subtype being diffuse large B cell (11 out of 21 cases for which histological subtype was available). Twenty two of the patients had died a median of 1.2 years after lymphoma diagnosis.

CONCLUSIONS

These data suggest aggressive disease in patients with SLE who develop NHL. Continuing work should provide further insight into the patterns of presentation, prognosis, and aetiology of NHL in SLE.

An international cohort study of cancer in systemic lupus erythematosus

OBJECTIVE

There is increasing evidence in support of an association between systemic lupus erythematosus (SLE) and malignancy, but in earlier studies the association could not be quantified precisely. The present study was undertaken to ascertain the incidence of cancer in SLE patients, compared with that in the general population.

METHODS

We assembled a multisite (23 centers) international cohort of patients diagnosed as having SLE. Patients at each center were linked to regional tumor registries to determine cancer occurrence. Standardized incidence ratios (SIRs) were calculated as the ratio of observed to expected cancers. Cancers expected were determined by multiplying person-years in the cohort by the geographically matched age, sex, and calendar year-specific cancer rates, and summing over all person-years.

RESULTS

The 9,547 patients from 23 centers were observed for a total of 76,948 patient-years, with an average followup of 8 years. Within the observation interval, 431 cancers occurred. The data confirmed an increased risk of cancer among patients with SLE. For all cancers combined, the SIR estimate was 1.15 (95% confidence interval [95% CI] 1.05-1.27), for all hematologic malignancies, it was 2.75 (95% CI 2.13-3.49), and for non-Hodgkin's lymphoma, it was 3.64 (95% CI 2.63-4.93). The data also suggested an increased risk of lung cancer (SIR 1.37; 95% CI 1.05-1.76), and hepatobiliary cancer (SIR 2.60; 95% CI 1.25, 4.78).

CONCLUSION

These results support the notion of an association between SLE and cancer and more precisely define the risk of non-Hodgkin's lymphoma in SLE. It is not yet known whether this association is mediated by genetic factors or exogenous exposures.

Atherosclerosis and systemic lupus erythematosus

The description of late-stage mortality and morbidity has been an important contribution to the understanding of systemic lupus erythematosus (SLE) in the past decade. Among the major factors in this clinical spectrum of SLE is the development of accelerated atherosclerosis. This condition has been recognized clinically with the documentation of myocardial infarction and angina in young women with SLE. This accelerated atherosclerosis has also been recognized at postmortem examinations. The exact mechanism for accelerated atherosclerosis remains unclear. However, disease activity with its immunologic events, the anticardiolipin syndrome, and the effect of corticosteroids in promoting hyperlipidemia contribute to its development. It appears that SLE may be a risk factor, in addition to the usual risk factors for the development of atherosclerosis. It has recently been shown that antimalarials may prevent some of the hyperlipidemia caused by corticosteroids. As evidence for the presence of subclinical atherosclerosis in these patients is accumulating, earlier diagnosis and treatment of events may be possible, and preventive measures may be instituted earlier.

The development and initial validation of the Systemic Lupus International Collaborating Clinics/American College of Rheumatology damage index for systemic lupus erythematosus

OBJECTIVE

To develop and perform an initial validation of a damage index for systemic lupus erythematosus (SLE).

METHODS

A list of items considered to reflect damage in SLE was generated through a nominal group process. A consensus as to which items to be included in an index was reached, together with rules for ascertainment. Each center submitted 2 assessments, 5 years apart, on 2 patients with active and 2 with inactive disease, of whom 1 had increased damage and the other had stable disease. Analysis of variance was used to test the factors physician, time, amount of damage, and activity status.

RESULTS

Nineteen physicians completed the damage index on 42 case scenarios. The analysis revealed that the damage index could identify changes in damage seen in patients with both active and inactive disease. Patients who had active disease at both time points had a higher increase in damage. There was good agreement among the physicians on the assessment of damage in these patients.

CONCLUSION

This damage index for SLE records damage occurring in patients with SLE regardless of its cause. The index was demonstrated to have content, face, criterion, and discriminant validity.

Antineutrophil cytoplasmic antibodies in systemic lupus erythematosus

OBJECTIVE

To evaluate the prevalence of cytoplasmic (c) and peripheral (p) antineutrophil cytoplasmic antibodies (ANCA) using the indirect immunofluorescence (IIF) slide kit (INOVA) in patients with systemic lupus erythematosus (SLE) to correlate the presence of ANCA with disease activity and to determine if ANCA is associated with specific clinical manifestations.

METHODS

One hundred and fourteen consecutive patients with SLE seen at The Wellesley Hospital Lupus Clinic, Toronto, Ontario in May and June, 1992 were assessed clinically, and blood drawn for routine serology and ANCA. Disease activity was measured using the SLE Disease Activity Index (SLEDAI). ANCA was measured by IIF.

RESULTS

Of the 114 patients, 12 (10.5%) had c-ANCA and 29 patients (25.4%) had p-ANCA. The titers of ANCA varied from 1:20 to 1:160. SLEDAI was 0 in 6 patients (5%), and 108 patients had some disease activity. Eighty-eight patients (77%) had mild to moderate active disease (SLEDAI < 10), and 20 (18%) patients had severe active disease (SLEDAI > or = 10).

CONCLUSION

No correlation was found between the presence of ANCA and SLEDAI either when analyzed as active-inactive (p = 0.75) or when correlated with degrees of disease activity (1-10: > 10) (p = 0.77). No correlation was found between p and c ANCA and the presence of vasculitis, renal, or CNS disease at the time of the assessment or at any time during the course of the disease. Thus ANCA was not associated with SLE disease activity or the presence of vasculitis in SLE.

Monocyte procoagulant activity in glomerulonephritis associated with systemic lupus erythematosus

Monocyte infiltration and activation of the coagulation system have been implicated in the pathophysiology of glomerulonephritis. In this study, spontaneous procoagulant activity (PCA) was measured in circulating mononuclear cells to determine whether elevated PCA correlated with the presence of proliferative glomerulonephritis in patients with systemic lupus erythematosus (SLE). No increase in PCA was found in 20 patients with end-stage renal failure, 8 patients with glomerulonephritis without SLE, and 10 patients undergoing abdominal surgical or orthopedic procedures as compared with 20 normal controls. In eight patients with SLE but with no apparent active renal disease, PCA was not elevated above normal basal levels. Seven additional patients with SLE who had only mesangial proliferation on biopsy also had no increase in PCA. In contrast, eight patients with focal or diffuse proliferative lupus nephritis, and one patient with membranous nephritis who ultimately developed a proliferative lesion, had a marked increase in PCA with greater than 100 times the base-line levels. The activity was shown to originate in the monocyte fraction of the mononuclear cells and was shown to be capable of cleaving prothrombin directly. The prothrombinase activity was not Factor Xa, because it was not neutralized by anti-Factor X serum and was not inhibited by an established panel of Factor Xa inhibitors. Monocyte plasminogen activator determinations did not correlate with renal disease activity. We conclude that monocyte procoagulant activity, a direct prothrombinase, seems to correlate with endocapillary proliferation in lupus nephritis and could be a mediator of tissue injury.

Impaired antigen-specific suppressor cell activity in patients with systemic lupus erythematosus

Antigen-specific suppressor cell activity of peripheral blood mononuclear cells was investigated in twenty-nine patients with systemic lupus erythematosus (SLE) and sixteen normal, age- and sex-matched healthy controls. Suppressor cell activity was generated by priming peripheral blood mononuclear cells with high dose antigen (ovalbumin) and adding the washed primed or control (unprimed) cells to autologous optimally stimulated target plaque-forming cell (PFC) cultures. The ability of the primed cells to interfere with an optimal ovalbumin-specific PFC response in the target cultures was used as a measure of antigen-specific suppressor cell activity. The results demonstrated reduced suppressor cell activity in the SLE patients relative to controls--46.8 +/- 3.6% vs 63 +/- 2.4% suppression respectively (P less than 0.01). Consistent with reduced suppressor cell activity was an increase in the plaque-forming cell response to ovalbumin in patients relative to controls (880 +/- 73 vs 763 +/- 102 PFC/10(6) cells respectively [P = 0.10]). No correlation was demonstrated between suppressor cell activity in SLE patients and disease activity or therapy.

Studies into the occurrence of soluble antigen-antibody complexes in disease. VI. Further characterization of the biological and physical properties of the rheumatoid biologically active factor (RBAF)

The rheumatoid biologically active factor (RBAF) was characterized further with respect to its biological and physical characteristics. The histamine-releasing activity of the RBAF in the guinea-pig lung was influenced in the same manner as soluble immune complexes when the lungs were being perfused at 20°C or 45°C or when the perfusate lacked calcium or magnesium or contained N-ethylmaleimide, phenol, theophylline, adrenaline or succinate. The RBAF was consistently associated with complement-fixing activity and RBAF-positive synovial fluid showed a lower total haemolytic complement level than RBAF-negative fluid. However, RBAF activity was not lost following absorption with anti-human beta 1C globulin. There was a higher frequency of free DNA and/or single-stranded DNA in RBAF-positive than negative synovial fluid. RBAF-positive synovial fluid was more active than RBAF-negative fluid in neutrophil chemotaxis when examined at 1:10 but not when undiluted. Mixed IgG–IgM cryoprecipitates failed to show RBAF activity and aggregates seen on analytical ultracentrifugation of rheumatoid synovial fluid did not correspond with the RBAF. The RBAF was stable to freezing and thawing but was labile to acid pH and to heating at 56°C. It was concluded that the RBAF is likely to be a soluble immune complex consisting of IgG and a second constituent which is labile to acid and heat.