Significance of plasma copper and caeruloplasmin concentrations in rheumatoid arthritis

Drugs and Conditions That May Mimic Hemolysis

OBJECTIVES

Visual inspection of posttransfusion plasma for hemolysis is a key laboratory method in the investigation of possible acute hemolytic transfusion reactions (AHTRs). Many substances and physiologic conditions can mimic hemolysis in vitro. Isolated reports describe specific cases of interference, but a comprehensive listing is lacking.

METHODS

Using an illustrative case, we summarize available literature on substances and conditions that may mimic hemolysis in vitro. We further describe other substances and conditions that may discolor plasma but are unlikely to be mistaken for hemolysis on visual inspection.

RESULTS

At least 11 substances and conditions have been reported to discolor plasma, in colors ranging from orange to red to brown, including relatively common therapies (eg, eltrombopag, hydroxocobalamin, iron dextran). Other substances are unlikely to be encountered in everyday practice but may mimic hemolysis in particular patient populations. Additional substances may cause plasma discoloration, ranging from blue to green to white, and are associated with a wide variety of therapies and conditions.

CONCLUSIONS

An awareness of the possible preanalytic confounding factors that may mimic hemolysis can aid in the workup of a suspected AHTR. Review of the medical record, use of ancillary testing, and consideration for nonimmune causes of hemolysis can aid in ruling out AHTR.

Serum Copper as a Marker of Disease Activity in Rheumatoid Arthritis

INTRODUCTION

Copper is an important trace element for normal growth and development of the body. It is also essential for maturation of collagen tissues. The purpose of the study was to estimate the serum copper levels in rheumatoid arthritis patients and to see its association with the various parameters of disease activity.

MATERIALS AND METHODS

The study was carried out among 50 diagnosed rheumatoid arthritis patients (25 each of active disease & remission patients) and 50 age and sex matched controls. Fasting blood sample was collected for estimation of serum copper, haemoglobin level and ESR in the subjects.

RESULTS

Mean serum copper level in the case group was found to be significantly higher than that of the control group (p-value<0.001). This increase of copper level was more in active disease than those with remission (p-value < 0.0001). A significant positive correlation was found between serum copper level and ESR, serum copper level and morning stiffness and a negative correlation was found between serum copper level and haemoglobin level in rheumatoid arthritis patients.

CONCLUSION

In rheumatoid arthritis patients, serum copper level may be used as an additional biochemical marker for estimation of disease activity.

Copper and zinc body levels in inflammation: an overview of the data obtained from animal and human studies

The development of acute and chronic inflammatory processes induces, in the laboratory animal, a net accumulation of both copper and zinc in many body compartments, the inflamed area included. In rheumatoid arthritis, as well as in animal models, only plasma zinc concentration seems to be significantly correlated with disease severity, while the increase in total plasma copper could be described as an "all or nothing" phenomenon. Moreover, in rheumatoid arthritis, it appears that the disease develops and progresses without being linked to either copper or zinc deficiency conditions. Thus, it seems reasonable to suggest that a rationale for the use of copper and/or zinc in the treatment of inflammatory disorders can only be drawn from the intrinsic pharmacological properties of such trace elements, rather than from the need for their repletion.

Anaemia in rheumatoid arthritis: pathogenesis, diagnosis and treatment

The pathogenesis, diagnosis and treatment of the anaemia of chronic disorders (ACD) in rheumatoid arthritis (RA) were reviewed. Causes of anaemia other than ACD frequently present in RA. Decreased iron absorption was shown to be the result of active RA rather than a cause of ACD or iron deficiency. It has been hypothesized that bone marrow iron availability decreases due to decreased iron release by the mononuclear phagocyte system or that the anaemia in ACD is due to ineffective erythropoiesis; these remain controversial theories. Studies considering a decreased erythropoietin responsiveness have not produced consistent results. Erythroid colony growth is suppressed in vitro by interleukins and tumour necrosis factor but their role in vivo in ACD is unknown. The diagnosis of ACD is made by exclusion. Iron deficiency is detected by transferrin, ferritin, and cellular indices after adaptation of their normal values. Treatment of the anaemia consists merely of antirheumatic treatment. Iron administration is counterproductive since iron chelators or exogenous erythropoietin administration might increase erythropoiesis.

Caeruloplasmin concentration and oxidase activity in polyarthritis

Caeruloplasmin (Cp) concentration and oxidase activity have been shown to be elevated in rheumatoid arthritis (RA) and psoriatic arthritis, but normal in Reiter's syndrome, Behcet's syndrome and juvenile seronegative polyarthritis. Synovial fluid Cp was significantly depressed in comparison with serum Cp in RA. During second-line therapy in RA, Cp concentration and activity fell significantly (P less than 0.001), but the change in Cp did not correlate with plasma viscosity.

Copper and inflammation--a possible rationale for the pharmacological manipulation of inflammatory disorders

Acute and chronic inflammations are characterized, among other features, by changes in the metabolism of copper and by a widespread responsiveness to the therapy with copper-containing molecules. The exact map of inflammation-induced copper movements as well as the role played by the metal in the pathogenesis of inflammatory disorders are, however, far from being clear, and this is especially true in the case of chronic processes. Nevertheless the present knowledge suggests that the "copper approach' may provide a new way for coping with the problem of anti-inflammatory/anti-arthritic therapies. The administration of exogenous copper, and the in vivo manipulation of the endogenous metal levels are proposed as two possible therapeutic strategies, not necessarily mutually exclusive. For a better understanding of the value of such an approach, further research work is needed, especially to attain a more detailed know-how on the involved chemical forms, distribution and functions of copper in both normal as well as inflamed organisms.

Serum copper and ceruloplasmin levels in rheumatoid arthritis and degenerative joint disease and their pharmacological implications

Serum copper concentration and ceruloplasmin activity were measured in patients with clinically established rheumatoid arthritis (R.A.) during the active phase, in patients with degenerative joint disease (D.J.D.) and in normal subjects. Copper and ceruloplasmin serum levels are significantly increased (P less than 0.01) in the arthritic group, but not in the degenerative joint disease group. Copper and ceruloplasmin levels are high significantly correlated in all the groups. This parallel enhancement of serum copper and ceruloplasmin in R.A. is commented in view of a possible protective role of endogenous copper and/or ceruloplasmin in inflammation.

Serum copper: a marker of disease activity in rheumatoid arthritis

Serum copper concentrations were measured in patients with rheumatoid arthritis (RA), ankylosing spondylitis (AS), osteoarthritis (OA), and in healthy controls. Median serum copper concentrations were raised significantly in RA and AS, but not in OA. Serum copper in RA correlated significantly with a number of disease activity markers--for example erythrocyte sedimentation rate (ESR), C-reactive protein, haemoglobin concentration, morning stiffness, and grip strength. It also correlated well with the overall disease activity as assessed by a composite index. Raised serum copper was associated with severe RA as manifested by the presence of immunoglobulin M rheumatoid factor, extra-articular features, weak grip and highly active disease. High serum copper might be related to the development of the pathological lesions observed in RA and not just be a secondary response.

The effect of drugs on serum histidine levels in rheumatoid arthritis

Groups of 15 patients with active rheumatoid arthritis were treated for 24 weeks with zinc sulphate, trien, captopril, clozic in two doses or a combination of D-penicillamine and hydroxychloroquine. Serum histidine levels were monitored along with measures of disease activity including C-reactive protein, plasma viscosity, articular index, grip strength and early morning stiffness. Zinc sulphate and trien were found to be ineffective while the other drugs all showed evidence of second-line action. Serum histidine was found to improve during successful therapy. The possible cause of low serum histidine and its response to therapy is discussed.

Ion-specific electrode study of copper binding to serum albumins

The binding of copper to bovine, human, rabbit, rat, and porcine albumin has been studied using a cupric ion-specific electrode. The results were analyzed in terms of Scatchard expression assuming two classes of independent binding sites. The high-affinity constants for copper binding to the albumin show the same trend as the first association constants for nickel binding, namely, rabbit greater than human greater than rat greater than pig. Despite the similarity in the primary amino acid sequence for human and bovine serum albumin, the former has only one high-affinity site for copper, while the latter has more than three sites.

Ceruloplasmin: an acute phase reactant that scavenges oxygen-derived free radicals

Superoxide anion radicals have been implicated recently as mediators of inflammation and tissue injury. Protection from superoxide anion radicals is provided primarily by a copper-containing, intracellular enzyme (superoxide dismutase) (SOD) that catalyzes the dismutation of superoxide to hydrogen peroxide and oxygen. We have found that the action of cytoplasmic SOD to scavenge superoxide and thereby to inhibit superoxide-mediated reactions can be mimicked by the copper-containing plasma protein and acute-phase reactant, ceruloplasmin. Ceruloplasmin, at concentrations present in normal plasma, inhibited reduction of both cytochrome c and nitroblue tetrazolium (NBT) mediated by the aerobic action of xanthine oxidase on hypoxanthine (a superoxide-generating system). Ceruloplasmin neither inhibited formation of uric acid by xanthine oxidase nor accelerated autooxidation of cytochrome c. Furthermore, in an experimental system in which contact between ceruloplasmin and indicator was prevented by a relatively impermeable lipid membrane barrier, ceruloplasmin inhibited reduction of NBT trapped within liposomes exposed to xanthine oxidase and hypoxanthine. Ceruloplasmin also inhibited reduction of cytochrome c and NBT mediated by the aerobic action of xanthine oxidase on acetaldehyde (another superoxide-generating system) and mimicked the activity of purified human erythrocyte SOD by inhibiting photoreduction of NBT and by accelerating aerobic photooxidation of dianisidine. Ceruloplasmin could be separated from purified human erythrocyte SOD by electrophoresis on alkaline 12% polyacrylamide gels and identified by its superoxide-scavenging activity. These results suggest that ceruloplasmin may function as a circulating scavenger of oxygen-derived free radicals.

Concerning the role of endogenous copper in the acute inflammatory process

The development of two models of acute inflammation (carrageenan-induced foot oedema and pleurisy) was studied in rats after 1 month of a 0.2 p.p.m. copper-deficient diet and after 5 months of a 0.6-0.8 p.p.m. copper-deficient diet. A 'pro-inflammatory' effect of copper deficiency was observed with the 0.2 p.p.m. diet, whilst no effect was evident following the 0.6-0.8 p.p.m. copper deficient diet. These results are briefly commented upon.

An evaluation of the use of electrophoresis and carbon furnace atomic absorption spectrometry to determine the copper level in separated serum protein fractions

The results of an evaluation of the use of atomic absorption spectrometry with carbon furnace atomisation to analyse the copper content of individual protein fractions separated by electrophoresis is reported. Albumin copper levels in patients with rheumatoid arthritis were found to be about 1 to 2% of the total serum copper. Both albumin and alpha 2 levels are affected by contamination from residual copper present on the strip. An investigation of this contamination indicated very low blank copper levels in the areas of the strip containing alpha 1 and beta proteins. These results, and the results of analysis of copper in the ultrafiltrate from the same serum samples, are combined to define the copper distribution in a group of patients with rheumatoid arthritis. The determinations that can most readily be carried out by this technique are discussed.

Serum copper and its relationship to clinical symptoms in rheumatoid arthritis

Total serum copper and ultrafilterable copper levels in patients with rheumatoid arthritis were determined and related to articular index, erythrocyte sedimentation rate (ESR), and serum iron concentration. Relationships were found between serum copper and ESR, and between ultrafilterable copper and articular index. The relationship between serum copper and serum iron was found to be a drug-dependent.

Serum copper and related variables in rheumatoid arthritis

Serum copper, caeruloplasmin, iron, iron-binding capacity, and antioxidant activity were measured in 120 normal subjects and in 189 patients with rheumatoid arthritis. Both serum copper and serum caeruloplasmin were significantly raised in rheumatoid disease in both sexes. A significant inverse relation was found between serum iron and serum copper, and a strong direct correlation between serum antioxidant activity and caeruloplasmin.

Copper in ankylosing spondylitis and rheumatoid arthritis

To study the role of copper in inflammatory rheumatic diseases, serum copper, serum ceruloplasmin concentration, erythrocyte sedimentation rate, and radio-copper studies were performed in 11 male patients with ankylosing spondylitis, in 12 female patients with rheumatoid arthritis and in 7 normal male subjects. The occurrence of elevated serum copper and serum ceruloplasmin levels can be confirmed in our study for patients with ankylosing spondylitis and rheumatoid arthritis when compared with normal controls. A significant correlation was found for these parameters and the inflammatory activity, characterized by the erythrocyte sedimentation rate. If groups with similar inflammatory activity are compared, higher ceruloplasmin concentrations are found in ankylosing spondylitis than in rheumatoid arthritis, the plasma incorporation of radiocopper also being higher in ankylosing spondylitis patients. Therefore, and because of comparable total serum copper concentrations, the non-ceruloplasmin bound copper level is found to be significantly higher in rheumatoid arthritis patients than in the group of ankylosing spondylitis patients. The significant correlation between erythrocyte sedimentation rate and the cumulative 120-hour urine excretion of radiocopper is in good agreement with the chemical finding of an elevated urinary copper excretion found by others, supporting the concept that the elevation of serum and urine copper levels in inflammatory rheumatoid diseases can be considered as an acute phase response.

Determination of histaminase (diamine oxidase) activity by o-dianisidine test: interference of ceruloplasmin

Until now o-dianisidine was used as an indicator substance in a test system for the determination of diamine oxidase. More recently, however, this substance was also used to measure ceruloplasmin activity. A study of the test principles revealed that o-dianisidine was the one denominator for both enzymes. As it was found for diamine oxidase the indicator was oxidized via peroxidase mediated H2O2 cleavage. Ceruloplasmin, however, oxidized o-dianisidine directly with resulting free radical formation. An addition of histamine dihydrochloride or putrescine dihydrochloride to an incubation mixture, containing ceruloplasmin as enzyme and o-dianisidine or p-phenylene-diamine as substrates, produced an activation of the enzyme, being more than 10-fold in the presence of 1 X 10(-2) M putrescine at pH 7.0. It was assumed that an allosteric effect of the dihydrochloride component might be responsible for this activation. When the activity of purified diamine oxidase was determined by the o-dianisidine test and by the isotope assay, a very good correlation between both methods was found. But, in a mixture of diamine oxidase and ceruloplasmin, no differentiation between the two enzymic activities by the o-dianisidine test was possible. This observation demonstrated an interference of ceruloplasmin when the o-dianisidine method was used for the determination of diamine oxidase activity. To apply our findings also in vivo the amine oxidase activity increasing in guinea-pig plasma during inflammation, was determined by the o-dianisidine test and by specific methods for some amine oxidase. Despite an enhanced oxidation of the o-dianisidine observed, only an increase of ceruloplasmin activity was found. It was concluded that ceruloplasmin had no 'histaminase activity' as has been assumed by other authors using the o-dianisidine test.

Chrysotherapy. A prospective study

A 4-year prospective clinical study of chrysotherapy was designed to reexamine old beliefs and traditions, and to test potentially new approaches to chrysotherapy. The standard weekly dosage of 50 mg was compared to that based on 1 mg/kg body weight; no significant differences were found. The rapidly absorbed aqueous thiomalate was compared to the slowly absorbed oil repository thioglucose; the latter produced significantly less side effects and an appreciably higher percentage of improvement. Almost half (43%) of nonresponders on standard regimen had a satisfactory clinical response at higher dosage levels without increase in toxicity. Some of these findings vary so much with traditional beliefs and practices that the authors urge caution in their interpretation. But generally speaking these problems are technical and do not detract from the conviction that chrysotherapy is valuable and comparatively safe in the management of rheumatoid arthritis and that it deserves more widespread application in clinical practice.

Serum copper and caeruloplasmin in ankylosing spondylitis, systemic sclerosis, and morphea

Studies of serum copper and caeruloplasmin were performed in patients with ankylosing spondylitis, systemic sclerosis, and morphea. Mean levels of both were raised significantly in ankylosing spondylitis, with the greatest increases in the worst cases. In patients with systemic sclerosis there was a significant increase in the mean level of caeruloplasmin, but not of copper, although both were raised in the 2 patients with the most aggressive disease. No alterations were found in patients with morphea. The values in the patients overlapped considerably with the values in the control subjects. It is thought that the increase in serum copper is probably secondary to the increase in caeruloplasmin which occurs as a nonspecific response to inflammation.

Ambivalent role of copper in inflammatory disorders

Soluble copper (Cu) preparations are both acute/chronic irritants and effective anti-inflammatory agents in rats. Copper is a prevalent component in several folk remedies for arthritis. Patients with rheumatoid arthritis and ankylosing spondylitis are reported to have higher-than-normal levels of serum copper, mainly associated with albumin. The anti-arthritis drug, D-penicillamine (Pn), efficiently strips Cu from some of its (pharmacologically inert) storage forms, e.g. Cu-albumin, Cu-polynucleotides yielding low M.W. Cu-Pn complexes, which show anti-inflammatory activity (ca. 5 X phenylbutazone) in rats irritated with carrageenan, oleyl alcohol, sodium urate and adjuvants. Under certain conditions Pn also blocks the amine-oxidase activity of caeruloplasmin, a circulating copper protein which is elevated in inflamed animals (an 'acute phase reactant'). Drugs, nutritional factors and the disease process may all possibly affect the movement of copper in vivo between inert reversible pharmacoactive reversible toxic forms.