Methodologic issues in the measurement of interleukin-16 in clinical blood samples using immunoassays

High-Dose Dexamethasone Alters the Increase in Interleukin-16 Level in Adult Immune Thrombocytopenia

Adult primary immune thrombocytopenia (ITP) is an autoimmune-mediated haemorrhagic disorder. Interleukin-16 (IL-16) can directly affect cellular or humoural immunity by mediating the cellular cross-talk among T cells, B cells and dendritic cells. Several studies have focused on IL-16 as an immunomodulatory cytokine that takes part in Th1 polarization in autoimmune diseases. In this study, we investigated IL-16 expression in the bone marrow supernatant and plasma of ITP patients and healthy controls. What's more, we detected IL-16 expression in ITP patients with the single-agent 4-day high-dose dexamethasone (HD-DXM) therapy. In patients with active ITP, bone marrow supernatant and plasma IL-16 levels increased (P < 0.05) compared with those of healthy controls. In the meantime, the mRNA expression in BMMCs (pro-IL-16, caspase-3) and PBMCs (pro-IL-16, caspase-3 and T-bet) of ITP patients was increased (P < 0.05) relative to those of healthy controls. In patients who responded to HD-DXM therapy, both plasma IL-16 levels and gene expression in PBMCs (pro-IL-16, caspase-3, and T-bet) were decreased (P < 0.05). In summary, the abnormal level of IL-16 plays important roles in the pathogenesis of ITP. Regulating Th1 polarization associated with IL-16 by HD-DXM therapy may provide a novel insight for immune modulation in ITP.

Interleukin-16 gene polymorphisms rs4778889, rs4072111, rs11556218, and cancer risk in Asian populations: a meta-analysis

OBJECTIVES

Some polymorphisms of the interleukin-16 (IL-16) gene are associated with various cancers. To resolve inconsistencies in published data, we performed a meta-analysis of studies of IL-16 polymorphisms and cancer risk.

MATERIALS AND METHODS

Seven eligible studies pooling 1678 cases and 1937 controls were quantitatively analyzed to evaluate three IL-16 polymorphisms (rs4778889, rs4072111, rs11556218) and cancer risk. Hardy-Weinberg equilibrium (HWE) for controls was evaluated by goodness-of-fit chi-squared tests. Odds ratios (ORs) and their 95% confidence intervals (CIs) were calculated for each genetic model and allelic comparison. Data were pooled using fixed- or random-effects models depending on heterogeneity across studies.

RESULTS

Our meta-analysis demonstrated that the IL-16 polymorphism rs11556218 was significantly associated with increased susceptibility to cancer in several models, including allelic contrast (OR=1.307; 95% CI, 1.108-1.541), heterozygote contrast (OR=1.650; 95% CI, 1.424-1.911), and dominant model (OR=1.605; 95% CI, 1.391-1.845). The result remained consistent after adjustment for age and gender. No significant association was found between IL-16 polymorphisms rs4778889 rs4072111 and cancer risk.

CONCLUSIONS

The rs11556218 T/G polymorphism of the IL-16 gene was significantly associated with elevated cancer risk in Asian populations. Our results warrant larger, better-designed studies, including a greater ethnic variety.

Integrative omics approach identifies interleukin-16 as a biomarker of emphysema

Interleukin-16 (IL-16) is a multifunctional cytokine that has been associated with autoimmune and allergic diseases. To investigate comprehensively whether IL-16 is also associated with chronic obstructive pulmonary disease (COPD) and emphysema, we performed an integrated analysis of multiple "omics" data. Over 500 subjects participating in the COPDGene® study donated blood and were clinically characterized and genetically profiled. IL-16 mRNA levels were measured in peripheral blood mononuclear cells (PBMC), and protein levels were measured in fresh frozen plasma. A multivariate analysis found plasma IL-16 positively associated with age and body mass index, and negatively associated with current smoking and emphysema in the upper lobes. PBMC IL-16 expression was positively associated with gender and a composite score for airflow obstruction, emphysema, and gas trapping. Whole-genome expression quantitative trait locus (eQTL) analysis identified a novel IL-16 missense SNP (rs11556218) associated with lower IL-16 in plasma. In summary, an integrated "omics" analysis in a very large cohort identified an association between decreased IL-16 and emphysema and discovered a novel IL-16 cis-eQTL. Thus IL-16 plasma levels and IL-16 genotyping may be useful in a personalized medicine approach for lung disease.

Normative levels of Interleukin 16 in umbilical cord blood

OBJECTIVES

The need for early and accurate prediction of outcome in hypoxic-ischaemic encephalopathy (HIE) remains critical. We have previously demonstrated that Interleukin 16 (IL-16) is raised in the umbilical cord blood (UCB) of infants with moderate and severe HIE and has the potential to be developed as a predictive biomarker. Normal reference ranges for IL-16 in UCB have not been previously described. The aim of this study was to determine normative levels of IL-16 in full term neonates using UCB following uncomplicated deliveries and to examine the effect of labour on cord IL-16 values.

DESIGN AND METHODS

Full term infants were recruited as part of an ongoing birth cohort study, the Cork BASELINE Birth Cohort Study. All had UCB drawn and bio-banked at -80°C, within 3hours of birth. Samples for this experiment were chosen from this population based cohort study to represent uncomplicated pre-labour caesarean sections and spontaneous vaginal deliveries. Analysis was performed on plasma EDTA, using ELISA Quantikine® (R&D Systems, Europe).

RESULTS

Samples were analysed from 48 infants with two modes of delivery; spontaneous vaginal delivery (n=12 male, n=12 female) and elective caesarean section (n=12 male, n=12 female). The range of all samples was normally distributed between 87.0 and 114.6pg/ml. Overall mean (SD) for IL-16 was 102.9 (21.5) pg/ml. Levels were not affected by spontaneous vaginal delivery or gender.

CONCLUSION

For the first time we have described the expected range of cord plasma IL-16 levels in healthy term infants following pre-labour and post-labour delivery.