Whole blood interleukin-8 concentrations in capillary and cord blood of neonates for the diagnosis of systemic inflammatory states.
An assay is described for the determination of interleukin 8 (IL-8) in whole blood lysate instead of plasma or serum. EDTA-anticoagulated umbilical cord blood or capillary blood was added to a detergent-containing lysing reagent. This sample was used directly for determination of IL-8 using the Immulite IL-8 assay kit (DPC, Bad Nauheim, Germany) and the Immulite Analyzer. Linearity was confirmed for cord blood as well as for venous blood, at a whole blood to lysing agent ratio from 1:20 to 1:1. IL-8 was stable in whole blood hemolysate at 4 degrees C for at least 3 days; thereafter, concentrations decreased remarkably to 32% of the initial concentration after 8 days. Storage of whole blood prior to hemolysis led to increases in IL-8 concentrations of up to 4 fold the original values. The intra-assay CV was 3.4% (at 234 ng/l) and 7.4 % (at 1080 ng/l) using hemolysate samples. Inter-assay CVs of 13.3% (at 108 ng/l) and 11.7 % (at 506 ng/l) were found using control material. Concentrations of IL-8 in whole blood were significantly higher than in the corresponding plasma. In 70% of 135 apparently healthy neonates' cord blood samples, plasma IL-8 concentrations were below the detection limit of the assay (5 ng/l), whereas a range of 69 - 3150 ng/l IL-8 (median, 266 ng/l) was found in the hemolysate samples of these neonates. A preliminary reference range for IL-8 in whole blood may be set at 132 to 820 ng/l (5th and 95th percentile). In 78 neonates, IL-8 concentrations in hemolysate from capillary blood ranged from 120 ng/l to 2000 ng/A (median, 416 ng/l). The fact that concentrations of IL-8 can be determined using only a very small sample volume (10 microl of whole blood) makes the assay format especially suitable for use in neonatal intensive care.
Kohse
Klaus P
KP
Institut für Laboratoriumsdiagnostik und Mikrobiologie, Klinikum Oldenburg, Germany. kohse.klaus@klinikum-oldenburg.de
Carl
Angelika
A
Steinbach
Gerald
G
D001774:Blood Chemical Analysis / Q000379:methods / Q000592:standards; D001800:Blood Specimen Collection; D002196:Capillaries; D002457:Cell Extracts / Q000032:analysis; D005260:Female; D005312:Fetal Blood / Q000737:chemistry; D006801:Humans; D007231:Infant, Newborn; D016209:Interleukin-8 / Q000097:blood*; D008297:Male; D008833:Microcirculation / Q000737:chemistry / Q000473:pathology; D011933:Reagent Kits, Diagnostic; D012016:Reference Values; D015203:Reproducibility of Results; D018746:Systemic Inflammatory Response Syndrome / Q000097:blood / Q000175:diagnosis*
D002457:Cell Extracts; D016209:Interleukin-8; D011933:Reagent Kits, Diagnostic