Plasma Neopterin Research Articles

Evaluation of definitions and parameters for sepsis assessment in patients after cardiac surgery.

In 110 patients undergoing elective heart surgery on extracorporeal circulation, various parameters were studied regarding the early assessment of septic complications. In a first step, the Elebute score definition for postoperative sepsis validated in general surgery patients (score > or = 12) could be confirmed in an extended form (> or = 12 on > or = 2 days) for cardiac surgery patients. According to this definition (overall classification accuracy for clinically defined sepsis-related mortality: 94%), septic complications occurred in 16 patients and were associated with a significantly worse prognosis than in non-septic patients (mortality 69% vs. 1%, p < 0.0001). In contrast, SIRS (best classification criterion: positive on > or = 3 days) displayed a lower specificity for clinically defined sepsis-related mortality, at least during the early postoperative course (accuracy: 67%). Based on the Elebute score classification, other more practicable parameters were investigated regarding their usefulness for an early sepsis risk assessment in post cardiac surgical patients. Five additional severity scores (APACHE II, MOF-Goris, HIS, SAPS, SSS) were comparable (ROC area: 0.94 to 0.96) and superior to plasma PMN-elastase and neopterin, haemodynamics and clinical parameters in predicting the risk for septic complications as early as by the first postoperative day.

Free radical activity and loss of plasma antioxidants, vitamin E, and sulfhydryl groups in patients with burns: the 1993 Moyer Award.

This study examines the relationship of burn injury and plasma levels of conjugated dienes, total sulfhydryl groups, and vitamin E in patients with thermal injuries. Plasma neopterin levels were determined as an index of macrophage activity and serine elastase as an index of polymorphonuclear cell activation. Thirteen patients with burns, six survivors and seven nonsurvivors, were studied for the first 4 days, then every other day until postburn day 14. Twelve healthy volunteers served as the control group. Survivors had 56% +/- 4% total body surface area burned, and nonsurvivors had 63.9% +/- % total body surface area burned. The patients with burns, compared with the control group, showed elevated plasma levels of the lipid peroxidation products conjugated dienes (0.767 +/- 0.045 vs 0.269 +/- 0.013 Abs at 233 nm) and reduced levels of the natural scavengers of free radicals, vitamin E (196.2 +/- 12.6 vs 841.1 +/- 22.7 micrograms/dl) and total sulfhydryl groups (54.0 +/- 0.4 vs 15.8 +/- 1.0 mumol/dl). The total sulfhydryl groups/conjugated dienes ratio fell at a greater rate (9.8% +/- 3.2% vs 3.2% +/- 0.7%/day) in nonsurvivors than in survivors (p < 0.05 by Mann-Whitney). The levels of elastase were slightly elevated in the patients with burns, but there was no difference between survivors and nonsurvivors. Normal neopterin levels are 3 to 10 nm/L; peak levels were 119 +/- 48 nm/L in nonsurvivors and 37.4 +/- 10 nm/L in survivors. Patients with burns demonstrated evidence of increased oxygen free radical activity and activation of polymorphonuclear cell and macrophages. Nonsurvivors demonstrated increased consumption of antioxidants compared with survivors.(ABSTRACT TRUNCATED AT 250 WORDS)

Thermal injury-associated neopterin production: regulation by interleukin-2.

Pteridin neopterin production by monocytes/macrophages has been linked to the biologic activity of immune activation- and/or infection-related cytokines. In patients with thermal injuries who succumb to infections, serum levels of both interleukin-2 (IL-2) and neopterin are significantly increased. However, the relationship between these two markers of immune activation remains unclear. This study examines the role of IL-2 in the biosynthesis of neopterin after major burn. Up to 4 weeks after burn, the levels of plasma neopterin and endotoxin were elevated in all patients studied (N = 9, 30% to > 90% total body surface area). Intact (unsupplemented) peripheral blood mononuclear cell (PBMC) cultures from patients with sepsis secreted high levels of neopterin spontaneously. The spontaneous release of neopterin was significantly decreased (p < 0.05) after supplementation with exogenous IL-2. The reverse was observed in peripheral blood mononuclear cell cultures from infection-free or control groups where relatively low neopterin secretion was markedly augmented in the presence of IL-2. The effect of IL-2 in patient cultures was unrelated to the activity of endogenous interferon gamma, because the production of this cytokine was profoundly reduced. However, IL-2-induced alterations in neopterin secretion paralleled those in the production of tumor necrosis factor alpha. This suggests that after thermal injury, biologic responses of neopterin-secreting peripheral blood mononuclear cells are directly or indirectly regulated by IL-2.

The influence of hypercholesterolemia on some aspects of immune pattern in the elderly

In order to investigate if age related dislipidemia was associated with immunological changes in vivo, humoral, soluble and cellular immune parameters were evaluated both in elderly with and without hypercholesterolemia and in young adults. Significantly increased IgG and IgA values were found in hypercholesterolemic aged compared to the other groups. Increased plasma neopterin levels (a pteridine generally used as a marker of macrophage activity) were reported in healthy aged subjects, whereas a lesser degree of the activation of the macrophage system was found in the hypercholesterolemic aged subjects. Compared with the young controls, an increase of interleukin 2 receptor expressing cells and of the IL-2 soluble receptors was noticeable in healthy aged subjects, whereas in hypercholesterolemic aged subjects only a minor increase of the IL-2 membrane receptor was noticed. We suggest that hypercholesterolemia may play a role in immune function in aging.

Neopterin plasma levels in burn patients

Burn victims have severely depressed cellular immunity and despite careful hygiene, antibiotics and early surgical therapy the infection rate remains high. The assessment of plasma neopterin levels can be considered as an indirect measurement of macrophage function, because activation of macrophages is accompanied by the release of d-erythro-neopterin. The influence of burn trauma on neopterin levels was investigated to determine whether neopterin estimations might have a prognostic or diagnostic value. Twenty patients with a mean age of 36 ± 16 years and a TBSA of 45.5 per cent ± 23 were studied. During the whole hospital treatment daily blood samples were analysed for neopterin levels using radioimmunoassay. Starting from normal levels (9 ± 1.6 nmol/l), neopterin content increased continuously until day 10 (30–40 nmol/l), then fluctuated around these high levels for several weeks. There were no differences between patients with TBSA < 35 per cent or > 35 per cent, and between survivors and non-survivors. Burn injury caused a constant increase of plasma neopterin indicating an intact reaction by macrophages. It can be used as an additional parameter for the diagnosis of sepsis: high values being a sign of adequate reaction by macrophages, whereas low neopterin values in the presence of bacteraemia and clinical symptoms of sepsis show a deleterious impairment of immune functions.

Enhanced release of cytokines, interleukin-2 receptors, and neopterin after long-distance running

This study was designed to examine cytokine production in a group of 22 well-trained runners covering a distance of 20 km within 2 hr. After running, all participants displayed a marked granulocytosis for 7 hr. Plasma neopterin levels increased 1 hr after exercise for 24 hr. Except for interleukin-6 (IL-6), cytokines were not reliably detected in plasma but were present in urine. Already before exercise, cytokines were detected in the urine of runners when compared to sedentary controls. Directly after running, interferon-γ and tumor necrosis factor-α were further elevated but rapidly declined to preexercise levels. Interleukin-1β and interleukin-6 increased at a slower rate after exercise but secretion into urine persisted longer until 12 and 7 hr, respectively. Interleukin-2 (IL-2) was not detected but soluble IL-2 receptors appeared in the urine directly after running. Enhanced cytokine levels were accompanied by an only low creatinin kinase increase, indicating little muscle damage. These data show that long-distance running elevates cytokine production which supports the concept that regular, but not excessive, physical exercise may be beneficial by maintaining a stimulated immune system.

Plasma Neopterin as an Adjunct to C-Reactive Protein in Assessment of Infection

C-reactive protein (CRP) concentrations are increased in plasma in people with inflammatory conditions and bacterial infections. Plasma neopterin concentrations are increased in people with bacterial septicemias, viral infections, and graft vs host disease. Plasma concentrations of CRP and neopterin were measured daily in 21 bone-marrow transplant (BMT) patients, 64 patients in intensive-care units (ICU), and 12 patients with squamous cell carcinoma of the head and neck (HN). In the BMT patients, plasma neopterin measurements in addition to CRP measurements allowed infectious episodes to be distinguished from graft vs host disease. In the ICU patients, increased concentrations of CRP were not specific for infection and the additional plasma neopterin measurements did not improve this specificity. In all three patient groups, the derivation of a neopterin/CRP ratio was of no clinical use. These three groups of patients showed patterns of CRP and neopterin concentrations characteristic of their underlying diseases, the BMT patients with the immunological activation of graft vs host disease showed predominantly increased concentrations of plasma neopterin, ICU patients with infectious and inflammatory conditions had increased concentrations of both CRP and neopterin in plasma, and the HN group with localized inflammation showed increased plasma concentrations of CRP without increases in neopterin.

The neonatal immune response to washed and irradiated red cells: lack of evidence of lymphocyte activation

A total of 21 neonatal infants (11 males and 10 females) were evaluated for lymphocyte subpopulation changes and cellular activation following the receipt of washed and gamma-irradiated red cells. The mean donor exposure was 2 +/- 1.5 donors, and the mean white cell concentration of each 10-mL-per-kg transfusion was 2 x 10(7) cells. A total of 2800 rad (28 Gy) was delivered to each red cell unit prior to washing. The lymphocyte subsets CD3+, CD4+, CD8+, CD19+, CD3+/CD25+, CD3+/HLA-DR, CD4+/CD45RA, CD4+/CDw29, and CD4+/ICHL-1 were analyzed, as were plasma gamma-interferon and neopterin levels, before and after blood transfusion. Posttransfusion samples were obtained from 3 to 12 days after the last blood transfusion. There were no posttransfusion changes in the percentage of lymphocyte subsets analyzed. Furthermore, overlay-histogram analysis of pretransfusion and posttransfusion CD45RA-, CDw29-, and UCHL-1-positive helper T cells failed to reveal a shift in mean channel fluorescence intensity, which is indicative of a lack of cellular activation. Gamma-interferon levels remained unchanged after transfusion (range, 90 +/- 5.9 to 95.5 +/- 5.3 pg/mL), as did neopterin levels (range, 3.7 +/- 1.5 to 4.6 +/- 1.5 ng/mL). This study could not find any evidence, by either cellular or humoral markers, of the activation of neonatal lymphocytes by transfusion. It is hypothesized that this failure to observe lymphocyte activation is due to the low number of donor white cells present in washed, irradiated red cells and/or to a lack of recipient recognition of transfused, allogeneic, donor white cells.

Levels of cytokines in plasma during Plasmodium falciparum malaria attacks

The variation of levels of tumor necrosis factor, granulocyte-macrophage colony-stimulating factor, gamma interferon, neopterin, and interleukin-2 receptors in plasma were monitored in 16 patients presenting with an acute Plasmodium falciparum malaria attack. Relations among cytokine levels and between cytokine levels and hematological and parasitological data were assessed.

Elevated serum neopterin levels in atherosclerosis

Plasma levels of neopterin were determined in patients with different clinical stages of atherosclerosis. Non-hospitalized patients with atherosclerosis had serum and plasma neopterin levels within the normal range of the assay (6 ± 2 nM). These values were not significantly different from those reported for healthy blood donors (5 ± 2 nM). In contrast, about 50% (29 out of 61) of hospitalized patients undergoing conservative or surgical therapy had neopterin plasma levels, which exceeded the normal range (> 10 nM) up to 10-fold. The two groups differ on a significance level of P < 0.01. For further evaluation hospitalized patients were subgrouped according to neopterin levels. In the subgroup with elevated neopterin levels patients with higher Frederickson types of atherosclerosis were overrepresented compared to patients with normal neopterin levels. Type 4 differed significantly from patients without pathological changes of lipoprotein ( P < 0.05). Only 3 patients suffered from minimal skin necrosis, two of them had elevated neopterin levels. Significantly more patients with peripheral artery occlusions had elevated neopterin levels than patients with occlusions of central arteries ( P < 0.05). All other criteria used for comparison (sex, age, smoking, antioxidant status, diabetes, hypertension, adipositas, hyperuricemia) did not vary significantly in both subgroups. These data indicate that neopterin plasma levels might be a valuable parameter in activity staging and therapeutic follow up of atherosclerosic patients. Additionally, an involvement of the nonspecific immune system in atherogenesis is suggested by the increased plasma neopterin concentrations.

Plasma Neutrophil-Activating Peptide-1/lnterleukin-8 and Neutrophil Elastase in a Primate Bacteremia Model

A hyperdynamic sepsis model was set up in seven adult baboons to evaluate neutrophil-activating peptide-1/interleukin (IL)-8 (NAP-1/IL-8), IL-1 beta, IL-6, tumor necrosis factor-alpha (TNF alpha), and IFN-gamma in plasma. By continuous intravenous administration of 10(10) cfu/kg live Escherichia coli over 8 h with additional infusion therapy (less than or equal to 50 ml/kg/h), endotoxin plasma levels of 2.7-22.3 ng/ml were observed. In plasma the kinetics of NAP-1/IL-8 and IL-6 were similar to those of IL-1 at the end of the experiment (8 h) (peak median values, 34, 4197, and 230 ng/ml, respectively). Differences were greatest for IL-6. Monocyte activation during sepsis was confirmed by elevated plasma neopterin levels (91-139 mumol/mmol of creatine). Granulocyte activation was evident from both incipient neutropenia and the massive release of neutrophil elastase into the plasma as measured by a new immunoassay (peak level, 374 ng/ml). Thus, in primate bacteremia, early TNF release is followed by a concomitant increase of NAP-1/IL-8 with plasma kinetics similar to those of IL-6 and IL-1 and accompanied by massive activation of neutrophils.

Immune Activation during Measles: Interferon- and Neopterin in Plasma and Cerebrospinal Fluid in Complicated and Uncomplicated Disease

To study T cell and macrophage activity during measles, levels of interferon-gamma (IFN-gamma) and neopterin in plasma and cerebrospinal fluid (CSF) were measured. Plasma levels of IFN-gamma were elevated in measles (1.17 +/- 0.27) compared with healthy adults (0.13 +/- 0.06, P less than .05) and children (0.14 +/- 0.06, P less than .01). Plasma levels of neopterin were elevated in measles (32.5 +/- 2.7) compared with healthy adults (5.3 +/- 2.9, P less than .0001), healthy children (12.1 +/- 4.0, P less than .001), and children with other infectious diseases (20.6 +/- 4.0, P less than .02). IFN-gamma was increased in measles primarily during rash; neopterin remained elevated for several weeks. Levels of neopterin showed a significant positive correlation with plasma levels of soluble interleukin-2 receptor and soluble CD8, two other parameters of T cell activation. Children with measles complicated by pneumonia had higher levels of neopterin in serum than those with uncomplicated disease. Children with measles complicated by autoimmune encephalomyelitis had higher levels of neopterin in CSF than those with noninflammatory neurologic disease but lower than those with central nervous system infections. Thus, IFN-gamma seems to be produced in vivo during acute measles virus infection; deficiency of this lymphokine does not appear to correlate with increased susceptibility to secondary infections.

Neopterin plasma levels during and after extra-corporal circulation (ecc) in uncomplicated cardiac surgical patients

Neopterin plasma levels during and after extra-corporal circulation (ecc) in uncomplicated cardiac surgical patients

Assessment of plasma neopterin in clinical kidney transplantation.

Serial plasma samples of 172 kidney transplant recipients and 42 chronic dialysis patients were evaluated retrospectively in a radioimmunoassay to determine the clinical relevance of plasma neopterin levels. Dialysis patients had a higher neopterin level 196 +/- 82 nmol/L (mean +/- SD) than 70 healthy controls (7 +/- 4 nmol/L). In 45 patients with a completely uneventful postoperative course, elevated pretransplant neopterin levels dropped rapidly within a week to a mean of 30 nmol/L and remained stable thereafter. In 22 outpatients with stable graft function there was a highly significant correlation between 170 paired serum creatinine and plasma neopterin values (r = 0.94). A group of 13 patients had experienced delayed graft function (ATN) without rejection. Their one-week mean neopterin level was 100 nmol/L and continued to drop in parallel with the serum creatinine. Another 15 patients rejected their kidneys irreversibly within 3 weeks-6 of them had extremely high neopterin levels during the rejection process (range 500-1000 nmol/L) that were not seen in other patients. A total of 169 rejection episodes in 43 patients were treated with bolus-dose cortisone. On the day of bolus therapy, both serum creatinine (P less than 0.002) and neopterin (P less than 0.005) were elevated. At 24 hours prior to bolus cortisone therapy, creatinine levels were not significantly elevated, whereas there was a significant rise in plasma neopterin (P less than 0.01). The overall sensitivity of neopterin increase was 86% with a 17% probability of false positives, and the sensitivity was 95% in biopsy-proved rejections. Plasma neopterin appears to be a useful marker for early detection of rejection and for identifying severe rejections that are not responsive to treatment.