[Neopterin, a new biochemical marker for clinical assessment of cell-mediated immune response]

Serum Neopterin Levels in Lung and Breast Cancer Patients Undergoing Radiotherapy And/Or Chemotherapy

The elevated neopterin levels observed in numerous haemotological diseases and parenchymatous malignomas suggested neopter in might be useful as a tumor marker. In a group of 60 patients suffering from advanced lung (18) or breast (42) cancer, serial determinations of serum neopterin were made before, during and after radiation and/or chemotherapy, during an observation period of 18 months, to check the potential value of neopterin in the therapeutic management of these tumor types. The neopterin profiles were compared with the clinical course and analysed with regard to response to therapy. Numbers of pathologically elevated serum neopterin levels were low. In only few cases was any agreement detected between changes in neopterin levels and therapeutic effects. Even chemotherapeutically induced depression in white blood counts generally did not increase serum neopterin levels. Thus the clinical suitability of neopterin as an adjuvant parameter in assessing therapeutic effects in lung or breast cancer could not be documented. (Int J. Biol Markers 1988; 3: 135-139)

Increasing plasma neopterin and persistent plasma endothelin during follow-up after acute cerebral ischemia

Release of inflammatory mediators from leukocytes and endothelial release of vasoactive factors are both important in the pathogenesis of atherosclerosis. To evaluate the concentrations of a specific marker for macrophage activation, neopterin, and the potent endothelial derived vasoconstrictive peptide endothelin-1 (ET-1), during the acute and chronic stages of cerebral ischemia, plasma concentrations of neopterin and ET-1 were measured in 59 patients with acute cerebral infarction or transient ischemic attack (median age 73 years, range 43-93, 27 men) and after a 1-year follow-up in 57/59 (97%) of patients. Plasma neopterin was higher at follow-up (6.3 nmol/L [3.7-21.6] vs 5.6 nmol/L [3.5-17.2]; p < 0.05) than at the acute stage, whereas the plasma ET-1 concentration was unchanged. Plasma concentrations of both neopterin and ET-1 correlated directly with age both in the acute stage (r = 0.42 and r = 0.35, respectively; p < 0.01) and after follow-up (r = 0.34; p < 0.05 and r = 0.27; p = 0.05, respectively). In conclusion, plasma neopterin increased after acute cerebral ischemia, indicating chronic inflammatory activity and continuous macrophage activation in ischemic cerebrovascular diseases.

Cytokine levels in acute alcoholic hepatitis: a sequential study

Chronic alcoholic liver disease is associated with several immunological alterations: depressed T-cell function, low serum gamma-interferon, and high serum tumour necrosis factor (TNF-alpha) and interleukin levels. Therefore, macrophage activity seems to be enhanced. Some cytokines, such as TNF-alpha, exert adverse effects on chronic alcoholic liver disease, so that protracted activation of macrophages with continuous TNF-alpha production may aggravate alcoholic hepatitis. Based on these facts we have sequentially determined serum levels of TNF-alpha, 1 beta interleukin (IL-1 beta), gamma-interferon and neopterin--a macrophage product--at admission, and at the end of the first, third and sixth weeks after admission, of 43 patients affected by alcoholic hepatitis, and of 20 age-matched sanitary workers as controls. Our patients showed higher levels of neopterin and lower levels of IL-1 beta and gamma-interferon than the controls; TNF-alpha levels in our patients were almost significantly higher than in controls. TNF-alpha levels at admission were higher in the patients who died (P = 0.025). TNF-alpha and neopterin levels showed no trend to normalization in patients who died, with higher levels of neopterin at first and third weeks and higher TNF-alpha and gamma-interferon levels at first week. Using logistic regression analysis, serum TNF-alpha levels at admission showed significant (P = 0.045), independent effects on mortality, as well as serum neopterin (P = 0.0026) at the first week. Thus, enhanced macrophage activity, measured by serum levels of TNF-alpha and neopterin seems to be related to a worse prognosis in alcoholic hepatitis.

High-performance liquid chromatographic measurement of cerebrospinal fluid tetrahydrobiopterin, neopterin, homovanillic acid and 5-hydroxindoleacetic acid in neurological diseases

Cerebrospinal fluid (CSF) samples from patients with a variety of neurological disorders were assayed to determine the concentrations of tetrahydrobiopterin (BH4), the active cofactor of hydroxylases. Dihydroneopterin (NH2) and neopterin (N), which are linked with BH4 synthesis and are inflammatory biochemical markers, were also measured simultaneously in a number of patients. 5-Hydroxyindoleacetic acid (5-HIAA) and homovanillic acid (HVA), the main products of serotonin and dopamine breakdown, were analyzed in parallel whenever possible. As BH4 and NH2 are difficult to analyze owing to their instability, CSF samples were collected under special conditions to preserve the reduced BH4 and NH2. Liquid chromatographic assays and detection of the various substances measured also required particular precautions. BH4 concentrations were elevated in patients with neurological disorders such as syphilis and lupus-like disease and especially in an AIDS patient with neurological complications with an increased N/BH4 ratio.

Correlation of interleukin-2 receptor and neopterin secretion in rheumatoid arthritis

In rheumatoid arthritis (RA) an immuno dysregulation alters the release of neopterin from human monocytes/macrophages, probably by activation of a feed-back regulation mechanism in pterin metabolism. With the overactivation of T-lymphocytes, the secretion of interleukin-2 and its receptor (IL-2R) is influenced. Investigation on 84 RA patients has shown that this immunoactivation is accompanied by an increased secretion of neopterin and soluble IL-2R in the serum, and that both parameters are very suitable for detection of inflammatory disease activity. The significant correlation between neopterin and IL-2R (r = 0.65; p < or = 0.001) in RA points out a possible connection in pathomechanisms of the immune system.

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 (greater than 10 nM) up to 10-fold. The two groups differ on a significance level of P less than 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 less than 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 less than 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 atherosclerotic patients. Additionally, an involvement of the nonspecific immune system in atherogenesis is suggested by the increased plasma neopterin concentrations.

Neopterin. A tumor marker in colorectal carcinoma?

Neopterin is compared with other tumor markers in colorectal carcinoma. Its sensitivity is clearly lower than that of CEA, TPA and CA 19/9 and is even lower than the sensitivity of the erythrocyte sedimentation rate. The ability of neopterin to discriminate between different tumor stages is also lower than that of the other markers. The discriminant analysis shows that measurement of neopterin in the serum of patients with colorectal carcinoma gives no essential additional information.

CSF neopterin as marker of disease activity in multiple sclerosis

Levels of neopterin, a factor known to be released from macrophages and monocytes at increased rates in cellular immune reactions, were higher in cerebrospinal fluid (CSF) in 10 of 12 patients with multiple sclerosis (MS) during exacerbations in comparison with remissions. This significant elevation in CSF during exacerbations was not reflected in serum. These results indicate that determination of neopterin in CSF may be a useful marker of disease activity in MS.

[Neopterin in the serum and urine in the differential diagnosis of disorders of kidney function following kidney transplantation]

In a period of 10 months neopterin in serum and urine was determined by radioimmunoassay in 33 renal allograft recipients treated with cyclosporin A. While in allograft rejections the highest neopterin concentrations were found in the serum, patients with viral infections after renal transplantation showed the most elevated concentrations in the urine. For early diagnosis of allograft rejection the ratio of neopterin clearance and serum-neopterin was the most significant criterion of the parameters measured in this study. Patients without complications during the follow-up showed slightly elevated and stable neopterin levels in serum and urine. The presented results indicate that neopterin is a useful parameter for the follow-up after renal allograft transplantation and for the diagnosis of immunological complications.

Urinary neopterin index as a measure of rheumatoid activity

The urinary neopterin index (U-NEOPT-I), expressed as micro-moles of neopterin/moles of creatinine) of 67 patients with definite or classical rheumatoid arthritis was significantly higher than that of sex- and age-matched persons or of 24 non-matched patients suffering from osteoarthrosis or arthralgia (2p less than 0.001). Furthermore, the patients with active disease had statistically significantly increased U-NEOPT-I when compared with patients with a clinically less active disease. In this study, the U-NEOPT-I value was the equal of CRP as a measure of rheumatoid activity. We suggest that neopterin might be involved in the pathogenesis of rheumatoid arthritis.

Neopterin as a new biochemical marker in the clinical assessment of ulcerative colitis

In previous publications we showed that neopterin, a pyrazino-pyrimidin compound, represents a biochemical marker for the assessment of cellular immune responses. We thought that the evaluation of this marker molecule might enable insight into the activity of cellular immune responses underlying ulcerative colitis (UC). Evaluation of urinary neopterin excretion in 25 consecutive untreated UC patients revealed striking correlations between neopterin levels and the severity of disease: elevated levels were observed in 9 out of 9 patients with moderately severe to severe, in 3 of 4 with mild and in none of 12 patients with quiescent disease. Further evidence for a correlation between disease activity and neopterin excretion was obtained on the basis of long-term follow-up studies performed in 4 cases. These studies indicated normalization of neopterin levels when clinical remission was achieved. Thereafter, the relative significance of neopterin excretion for determination of clinical stage was assessed by linear correlation analyses and was compared with conventional clinical parameters such as anemia, number of motions per day, raised temperature, ESR and extent of bowel involvement. The logarithm of neopterin excretion and the extent of bowel involvement were the two single parameters most closely related to the clinical stage of ulcerative colitis. We, therefore, conclude that evaluation of neopterin excretion in ulcerative colitis patients represents a new and useful tool for the clinical monitoring of disease activity.