Biological variation of immunological blood biomarkers in healthy individuals and quality goals for biomarker tests.

BACKGROUND: Cytokines, chemokines, adipocytokines, soluble cell receptors, and immune activation markers play an important role in immune responsiveness and can provide prognostic value since they reflect underlying conditions and disease states. This study was undertaken to investigate the components of biological variation for various laboratory tests of blood immunological biomarkers. RESULTS: Estimates of intra-individual coefficient of variation (CVI) and inter-individual coefficient of variation (CVG) were examined for blood immunological biomarkers. Biomarkers with CVI < 10% for both genders were CD3, CD4, and CD8 T-cells, serum levels of soluble cluster of differentiation 14 (sCD14), sCD163, and soluble glycoprotein 130 (sgp130). The CVI for serum levels of adiponectin, interleukin-1 receptor antagonist (IL-1Ra), macrophage inflammatory protein 1 beta (MIP-1ß), soluble CD40 Ligand (sCD40L), soluble interleukin-2 receptor alpha (sIL-2Rα), soluble interleukin-6 receptor (sIL-6R), soluble tumor necrosis factor receptor II (sTNF-RII), and tumor necrosis factor alpha (TNF-α) were between 11 and 20%. Biomarkers with CVG < 20% were CD3 T-cell, and serum concentrations of sCD14, sCD40L, and sgp130. The biomarkers with CVG > 40% were adiponectin, IL-1ra, leptin, MIP-1ß, sCD163, and sIL-2Rα. CONCLUSION: The biological variations of biomarkers have important monitoring value for longitudinal investigation and are essential for quality specification of tests that are performed in the laboratory. The CVI was relatively small while CVG was comparatively large and mean values of each biomarker vary between subjects. The individuality of biomarkers significantly influences reference interval values. A majority of the biomarkers in this study had strong individuality and the result of each biomarker should be cautiously interpreted if using established reference interval values. Comparison of a patient's test result with previous ones may be more useful than the usage of conventional reference values.

The influence of EDTA Vacutainer blood collection tube on the level of blood interleukin-1 receptor antagonist.

BACKGROUND: The use of anticoagulants may influence the composition of blood cells and interfere with plasma levels of IL-1ra when unprocessed EDTA blood samples are stored for long periods of time. METHODS: Blood was drawn into EDTA and heparinized blood collection tubes from 11 HIV-1 negative men participating in the Multicenter AIDS Cohort Study (MACS) and 4 healthy volunteers. The blood was processed according to the experiments detailed in the method and after incubation; supernatants were collected and stored at -70 °C until batch testing using IL-1ra ELISA. RESULTS: There was no difference between the levels of IL-1ra in EDTA blood collected into plastic and glass tubes (p = .911). There were significant increases from baseline levels of IL-1ra (p ≤ .05) after 24 h incubation for diluted whole blood and PBMC supernatants but not for granulocytes supernatants. CONCLUSION: EDTA as an anticoagulant influences the blood concentrations of IL-1ra in unprocessed blood. Thus, EDTA blood is not a suitable specimen for measurement of IL-1ra. Other types of anticoagulated blood should be processed within one hour of draw whenever measuring plasma levels of IL-1ra.