A. J. G. Swaak

Interleukin-6 (IL-6) in synovial fluid and serum of patients with rheumatic diseases.

Interleukin-6 (IL-6) is a monokine with a number of biological activities, which are intimately related to inflammatory responses. We have measured IL-6 levels in synovial fluid (SF) and serum (Se) of patients with rheumatic diseases. SF-IL-6 levels were a thousand-fold higher than corresponding Se levels and a positive correlation was found between SF and Se levels suggesting that Se-IL-6 is derived from IL-6 produced in the joint. Se levels of IL-6 were also positively correlated to C-reactive protein (CRP) levels, supporting the in vitro experiments showing that IL-6 stimulates hepatocytes to produce CRP. Finally we observed a positive correlation between SF-IL-6 levels and the local activity score.

Interleukin-6 (IL-6) and acute phase proteins in the disease course of patients with systemic lupus erythematosus.

SummaryOne of the mediators responsible for the induction of the production of acute phase proteins by hepatocytes is interleukin-6 (IL-6), formally known as hybridoma growth factor (HGF). In a prospective study the biological significance of IL-6, but also the relationship with the acute phase response (C-reactive protein [CRP], α1-antitrypsin and α1-acid glycoprotein) during flare-ups in 12 systemic lupus erythematosus (SLE) patients was investigated. Only 2 SLE patients showed sustained elevated IL-6 levels, and in one of these patients a clear correlation was found between the increases in IL-6 and the acute phase response. In the other SLE patients hardly any response or change in the levels of IL-6, CRP, and/or α1-antitrypsin was found. In contrast to the profiles of α1-acid glycoprotein, in seven of the SLE patients a significant increase in the serum levels took place in the period preceding the exacerbation. This difference between the three acute phase proteins suggests that the regulatory mechanisms are different. Our results are in agreement with the findings that IL-6 might be responsible for the CRP response.

An analysis of the levels of complement components in the synovial fluid in rheumatic diseases.

SummaryA linear relationship between the synovial fluid to serum concentration ratios and log molecular weight was found for six plasma proteins, which are largely synthesized by the liver. Production or utilization of a given protein in the joint can, therefore, be determined by its deviation from the calculated diffusion line. Based on this diffusion model the role of the complement system was investigated in the joint effusions of 48 patients with rheumatoid arthritis (RA), 6 patients with osteoarthritis (OA) and 7 patients with meniscus lesions (ML). Among these three groups quantitative differences were found in the metabolism or utilization of several complement components, based on the fact that the ratios were lower than expected for diffusion of proteins of similar molecular weight. The ratios for the RA group were the lowest. In the three patient groups, results showed increased consumption mainly of C3 and C4 locally in the joint. The existence of a real complement activation in the joints of the three different patient groups was further proved by the elevated levels of C3 breakdown products (C3d). Overall this kind of calculation provides us with a method for studying the role of other proteins which may be important in the inflammatory process of the joint.

Regulation of ferritin: a specific role for interferon-alpha (IFN-α)? The acute phase response in patients treated with IFN-α-2b

Background Adult onset of Still’s disease is characterized by very high serum ferritin levels, in disproportion with other acute phase proteins (APPs). Because interferon‐alpha (IFN‐α) was observed to cause hyperferritinaemia in three healthy people without increase of other APPs, we hypothesized that IFN‐α stimulates specifically the synthesis of ferritin. To test this hypothesis, we studied ferritin and other APP levels in patients treated with IFN‐α.

Complement (C3) metabolism in systemic lupus erythematosus in relation to the disease course

SummaryMetabolic turnover studies of complement components (C3) provide a direct insight into the dynamics of the complement regulation (synthesis and catabolism). To obtain information about the role of the complement system in relation to the disease course in patients with systemic lupus erythematosus (SLE), a prospective study was performed. The results of the C3 turnover studies were also correlated to the complement levels (C3) and to the presence of C3 conversion products (C3d) in circulation. In nearly all SLE patients (in 21 of the 26 metabolic turnover studies) a C3 hypercatabolism was found, with a quantitative difference depending on the disease phase. In the period preceding an exacerbation an impaired C3 synthesis was observed (in three of the four studies), in contrast to SLE patients in stable disease phase where in one case only a decrease C3 synthesis was calculated (1 out of 15 observations). A linear correlation was found between the serum C3-levels and the ratio of C3d/C3, suggesting that both serologic parameters are quantitatively indicative for C3 hypercatabolism. The study shows that in all SLE patients, irrespective of the disease stage, an increased C3 consumption is found, which supports the concept that a chronic inflammatory process is constantly present.

Changes of ferritin and CRP levels in melanoma patients treated with adjuvant interferon-α (EORTC 18 952) and prognostic value on treatment outcome

Adjuvant therapy with interferon-&agr; (IFN) only benefits a small subgroup of melanoma patients and a predictive marker selecting responders does not exist. IFN induces increased ferritin and decreased C-reactive protein (CRP) levels; however, an association with treatment effect was not studied. Serum was collected from patients participating in the European Organization for Research and Treatment of Cancer 18 952 trial comparing adjuvant treatment with IFN to observation. Serial ferritin and CRP levels were determined using enzyme-linked immusorbent assays, before treatment and up to 24 months. Ferritin levels are influenced by sex and age; therefore ratios of serial ferritin and CRP values with corresponding pretreatment values were calculated. Cox regression model and landmark method at end of induction and 6 months were used to evaluate the association between ferritin, CRP and distant metastasis-free survival (DMFS). Baseline ferritin levels were comparable in the two treatment groups (P=0.92). However, ferritin ratios were significantly higher in IFN-treated patients (N=96) compared with untreated patients (N=21) at end of induction (mean: 2.88 vs. 0.75; P=0.0003) and at 6 months (mean: 3.18 vs. 1.02; P=0.009). In the IFN arm, higher ferritin ratios at end of induction and at 6 months were not associated with improved outcome (respectively, P=0.66 and 0.86). Concerning CRP ratios, no differences between the treatment groups, neither an association with DMFS, were observed. Administration of IFN in melanoma patients induced increase in ferritin levels but not in CRP levels. Ferritin and CRP ratios have no prognostic value regarding DMFS.

Intrapleural administration of tumour necrosis factor alpha (TNFα) in patients with mesothelioma: Cytokine patterns and acute-phase protein response

Tumour necrosis factor‐alpha (TNFα) has been found to be very effective in the isolated limb perfusion setting for advanced extremity tumours. In a phase I study of intrapleural administration of TNFα 5 patients were followed for inflammatory response patterns.

Effects of isolated limb perfusion with tumour necrosis factor-alpha on the function of monocytes and T lymphocytes in patients with cancer

The objective of the present study was to investigate the effects of isolated limb perfusion (ILP) with tumour necrosis factor alpha (TNF‐α) and melphalan in patients with cancer on, first, plasma levels of cytokines, second, systemic monocyte and T‐lymphocyte distribution and, third, the ability of mononuclear cells to produce cytokines upon stimulation in vitro. Six patients undergoing an ILP were entered into the study (group 1). In addition, patients undergoing a major surgical operation (group 2), minor operation (group 3) as well as healthy volunteers (group 4) were included as control groups. Sensitive enzyme‐linked immunosorbent assays (ELISAs) were used to measure TNF‐α and interleukin‐6 (IL‐6) plasma levels at various time points during and after operation. Furthermore, the percentage of monocytes and T lymphocytes was determined in all studied groups using a FACScan. In addition, cytokine production upon stimulation with lipopolysaccharide (LPS) and a combination of anti‐CD3/anti‐CD28 monoclonal antibodies in whole‐blood cultures was investigated. Increased plasma levels of TNF‐α and IL‐6 in patients undergoing ILP was observed, but only IL‐6 appeared to be increased in patients treated with a major operation. No significant fluctuations were found in the other groups studied. Concerning the number of monocytes, a significant decrease was observed only in patients treated with ILP. Furthermore, a decreased production of TNF‐α, IL‐6 and IL‐8 upon various types of stimulation in vitro was found in those patients, but also after a major operation. In conclusion, the results of the present study show increased plasma levels of cytokines in patients treated with ILP and major operation. Furthermore, a decrease in numbers of monocytes in the circulation and the ability of mononuclear cells to produce cytokines in vitro may be induced by administration of TNF‐α in ILP. Although similar results were found in patients treated with major operation, the underlying mechanisms of this phenomenon remain to be elucidated.

Changes in clinical features of patients with systemic lupus erythematosus followed prospectively over 2 decades

SummaryIn the past decades the general concept of the disease course and the prognosis of systemic lupus erythematosus (SLE) has changed dramatically. The improvement in prognosis of our SLE patients is often said to be related to the growing awareness of the disease. This study focussed on whether or not the clinical features at the onset of the disease, and at diagnosis, and the clinical course as well as the age at the onset of the disease had changed during the past decades. No obvious differences were observed in the age at the onset of the disease or in the age at diagnosis. Of the 22 clinical signs studied, only the prevalence of Raynauds phenomenon at the onset of the disease had increased during the past 20 years. At diagnosis, the prevalence of oral ulcers and false positive syphilis test had decreased. Only small differences in the type but not in the number of exacerbations were observed; in the past 20 years, the prevalence of renal involvement increased from 20% to 43%. However, this was not significant. Our results did not support the theory that during the past 2 decades the disease had changed in its expression, neither did we find that the disease is presently diagnosed at an earlier age, as would be expected from the increased awareness of the disease.

Complement (C3) metabolism in rheumatoid arthritis in relation to the disease course

SummaryMetabolic turnover studies of the third component of complement, C3, were performed in 23 patients with rheumatoid arthritis (RA) to get a direct insight in the dynamics of complement synthesis and catabolism. Results of these turnover studies were related to the serum level of the total amount of C3 as well as to that of the activation product C3d. A hypercatabolism of C3 was observed in 12 of the 23 patients studied. Six of these 12 patients showed signs of extra-articular RA; only one patient with extra-articular manifestations had a normal catabolism of C3. Decreased serum levels of C3 were not found in any of the patients with a hypercatabolism of C3, indicating that the accelerated turnover was compensated by an increased synthesis. In RA patients levels of the activation product C3d could not correlate with the turnover of C3. However, in selected RA patients without signs of nodules or extra-articular manifestations, they could. Thus, our results indicate that serum levels of C3 and C3d do not reflect C3 metabolism in RA patients. Furthermore, the existence of extra-articular manifestations is accompanied by a more pronounced activation of the complement system.