Evidence for endotoxin contamination in plastic Na+-heparin blood collection tube lots.
BACKGROUND
Biomarker assays are often conducted on whole blood samples in the course of drug development studies. Because bacterial lipopolysaccharide (LPS) (endotoxin) contamination is known to cause spontaneous cytokine production by monocytes, contamination of blood collection tubes may interfere with biomarker assay results.


METHODS
Whole blood from healthy donors was collected into plastic or glass sodium (Na(+))-heparin Vacutainer() blood collection tubes and heparinized syringes. Samples were analyzed for phosphoprotein response, cytokine production, and RNA expression. Tubes were tested for endotoxin contamination by use of the limulus amoebocyte lysate assay.


RESULTS
Results of phospho-flow cytometry, branched DNA (bDNA), and ELISA assays indicated that a specific lot (#5339582) of plastic Na(+)-heparin Vacutainer tubes was highly contaminated with an endotoxinlike substance, and contamination was confirmed by the limulus amoebocyte lysate assay. Analysis of multiple-analyte panels revealed that analytes whose changed expression was predictive of LPS stimulation were increased when whole blood was incubated in contaminated tubes for 6 or 18 h. Two additional lots of plastic tubes tested had detectable amounts of endotoxin sufficient to strongly alter phospho-flow cytometry analyses, as determined by the fold change in phosphorylation of p38 mitogen-activated protein kinase in response to tumor necrosis factor alpha and LPS. In contrast, 3 lots of glass tubes had substantially lower levels of spontaneous blood activation.


CONCLUSIONS
Endotoxin contamination associated with tubes from 3 lots of a particular type of plastic Na(+)-heparin Vacutainer tube dramatically affected biomarker assay measurements. Prescreening these tubes is suggested before their use in clinical sample analysis.
Newhall
Kathryn J
KJ
Amgen Molecular Sciences, Amgen, Seattle, WA, USA. knewhall@amgen.com
Diemer
Geoffrey S
GS
Leshinsky
Natalia
N
Kerkof
Keith
K
Chute
Hilary T
HT
Russell
Chris B
CB
Rees
William
W
Welcher
Andrew A
AA
Patterson
Scott D
SD
Means
Gary D
GD
D000925:Anticoagulants; D015415:Biomarkers / Q000097:blood; D001800:Blood Specimen Collection / Q000295:instrumentation*; D002097:C-Reactive Protein / Q000096:biosynthesis / Q000235:genetics; D018932:Chemokine CCL2 / Q000097:blood / Q000235:genetics; D054410:Chemokine CCL7 / Q000097:blood / Q000235:genetics; D004731:Endotoxins / Q000032:analysis*; D004797:Enzyme-Linked Immunosorbent Assay; D004866:Equipment Contamination; D005434:Flow Cytometry; D006493:Heparin; D006801:Humans; D053583:Interleukin-1beta / Q000097:blood; D015850:Interleukin-6 / Q000097:blood / Q000235:genetics; D008070:Lipopolysaccharides / Q000494:pharmacology; D010766:Phosphorylation; D010969:Plastics; D012333:RNA, Messenger / Q000097:blood; D000683:Serum Amyloid P-Component / Q000096:biosynthesis / Q000235:genetics; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases / Q000097:blood; D000099153:Pentraxins
D000925:Anticoagulants; D015415:Biomarkers; D002097:C-Reactive Protein; D018932:Chemokine CCL2; D054410:Chemokine CCL7; D004731:Endotoxins; D006493:Heparin; D053583:Interleukin-1beta; D015850:Interleukin-6; D008070:Lipopolysaccharides; D010969:Plastics; D012333:RNA, Messenger; D000683:Serum Amyloid P-Component; D014409:Tumor Necrosis Factor-alpha; D048051:p38 Mitogen-Activated Protein Kinases; D000099153:Pentraxins