Neopterin concentrations in blood donors differ between AB0 blood group phenotypes

Serum Neopterin Is Not Influenced by Age and Blood Group of Transfusion-Transmitted Infection Negative Blood Donors

Objectives

To measure serum neopterin levels in blood donors of the local population and to study its relationship with age and blood group of transfusion-transmitted infection (TTI) negative blood donors.

Methodology

This cross-sectional study was carried out in the Department of Physiology at Liaquat National Hospital and Medical College (LNMC), Karachi, Pakistan, in collaboration with the Basic Medical Sciences Institute and Jinnah Post Graduate Medical Centre (JPMC). Data were collected from January 2018 to July 2018. A total of 174 blood donors participated in the study, who were selected by using a random sampling technique. They were screened through the standard procedures used for screening at the JPMC blood bank for TTIs as per the World Health Organization recommendations. Serum neopterin was estimated using enzyme-linked immunosorbent assay (ELISA) kits. Data analysis was performed using Statistical Package for Social Sciences (SPSS) version 23 (IBM Corp., Armonk, NY, USA). Chi-square and ANOVA (analysis of variance) were applied, and tests of significance were kept as P < 0.05.

Results

Neopterin level in the serum of TTI-positive blood donors was 15.1 ± 4.59 nmol/L, which was above the normal range and cutoff value of 10 nmol/L, whereas the neopterin level in the serum of TTI-negative blood donors was 6.1 ± 1.82 nmol/L (P = 0.001). In TTI-negative blood donors, the neopterin levels were within normal limits and were not influenced by age and blood groups (P > 0.05).

Conclusions

Serum neopterin levels did not report any significant difference in terms of age and blood group of TTI-negative blood donors and were seen to be within normal limits.

Interferon-gamma-inducible kynurenines/pteridines inflammation cascade: implications for aging and aging-associated psychiatric and medical disorders

This review of literature and our data suggests that up-regulated production of interferon-gamma (IFNG) in periphery and brain triggers a merger of tryptophan (TRY)-kynurenine (KYN) and guanine-tetrahydrobiopterin (BH4) metabolic pathways into inflammation cascade involved in aging and aging-associated medical and psychiatric disorders (AAMPD) (metabolic syndrome, depression, vascular cognitive impairment). IFNG-inducible KYN/pteridines inflammation cascade is characterized by up-regulation of nitric oxide synthase (NOS) activity (induced by KYN) and decreased formation of NOS cofactor, BH4, that results in uncoupling of NOS that shifting arginine from NO to superoxide anion production. Superoxide anion and free radicals among KYN derivatives trigger phospholipase A2-arachidonic acid cascade associated with AAMPD. IFNG-induced up-regulation of indoleamine 2,3-dioxygenase (IDO), rate-limiting enzyme of TRY-KYN pathway, decreases TRY conversion into serotonin (substrate of antidepressant effect) and increases production of KYN associated with diabetes [xanthurenic acid (XA)], anxiety (KYN), psychoses and cognitive impairment (kynurenic acid). IFNG-inducible KYN/pteridines inflammation cascade is impacted by IFNG (+874) T/A genotypes, encoding cytokine production. In addition to literature data on KYN/TRY ratio (IDO activity index), we observe neopterin levels (index of activity of rate-limiting enzyme of guanine-BH4 pathway) to be higher in carriers of high (T) than of low (A) producers alleles; and to correlate with AAMPD markers (e.g., insulin resistance, body mass index, mortality risk), and with IFN-alpha-induced depression in hepatitis C patients. IFNG-inducible cascade is influenced by environmental factors (e.g., vitamin B6 deficiency increases XA formation) and by pharmacological agents; and might offer new approaches for anti-aging and anti-AAMPD interventions.