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Table 2 Correlation between EDTA plasma versus serum biomarkers measured by Luminex xMap™, clinical research study subjects a (n = 18 pairs)

From: Temporal reliability of cytokines and growth factors in EDTA plasma

Biomarker Plasma Serum Plasma vs.
Serum Paired
Relative
Difference
(%)
p-value
(Wilcoxon Signed-
Rank Test)
Spearman
Correlation
Coefficient
(rs)
rs
p-value
  %
Above
LLD
Median (25%, 75%) %
Above
LLD
Median (25%, 75%) Median (25%, 75%)    
Cytokines            
hsIL-1β (pg/mL)b 100 5.1 (3.4, 7.5) 94.4 3.5 (2.5, 8.9) 14 (-14, 42) 0.548 0.83 0.000
hsIL-2 (pg/mL)b 100 18.8 (9.8, 25.7) 100 17.4 (7.4, 35.6) -2.3 (-39, 38) 0.799 0.69 0.002
sIL-2R (pg/ml)c 100 658 (602, 746) 100 660 (527, 831) -4.7 (-17, 11) 0.459 0.72 0.001
IL-4 (pg/mL)c 100 141 (108, 181) 100 113 (96.4, 123) 19 (-3.3, 46) 0.009 -0.02 0.922
hsIL-4 (pg/mL)b 100 56.3 (27.9, 91.4) 100 63.0 (34.4, 108) -15 (-41, 11) 0.159 0.28 0.265
hsIL-5 (pg/mL)b 100 2.3 (1.4, 3.1) 94.4 2.6 (0.8, 3.9) 11 (-16, 44) 0.459 0.77 0.000
hsIL-6 (pg/mL)b 100 20.3 (12.6, 35.7) 100 28.9 (13.3, 43.6) -2.2 (-41, 7.6) 0.369 0.77 0.000
sIL-6R (ng/mL)c 100 27.5 (26.0, 34.6) 100 59.1 (47.9, 91.9) -102 (-189, -68) 0.000 0.39 0.113
hsIL-7 (pg/mL)b 100 14 (9, 16.9) 94.4 14.8 (13.3, 18.6) -32 (-80, 5.3) 0.008 0.64 0.006
hsIL-8 (pg/mL)b 100 10.3 (6, 21.5) 100 13.3 (7.9, 26.2) -20 (-59, -1.8) 0.002 0.90 0.000
hsIL-10 (pg/mL)b 100 31.8 (19.9, 40.2) 100 25.5 (11.2, 48.8) 20 (-23, 30) 0.442 0.73 0.001
IL-12p40 (pg/mL)c 100 417 (361, 602) 100 417 (358, 537) -0.4 (-6.9, 3.0) 0.393 0.96 0.000
hsIL-12p70 (pg/mL)b 100 20.8 (14.8, 32.6) 100 29.1 (16.5, 59.9) -14 (-112, 1.3) 0.030 0.77 0.000
hsIL-13 (pg/mL)b 100 27.2 (19.6, 33.8) 100 32.6 (22.3, 53) -20 (-56, 14) 0.057 0.66 0.003
CRP (μg/mL)b 100 20.5 (7.4, 35.7) 100 22.2 (8.6, 40.2) -11 (-20, 4.1) 0.081 0.95 0.000
IFNα (pg/mL)c 100 42.7 (34.2, 53) 100 37.8 (34.2, 47.3) 4.1 (-20, 31) 0.318 -0.05 0.840
IFNγ (pg/mL)c 100 166 (125, 262) 100 83.0 (73.9, 91.1) 56 (20, 70) 0.000 -0.17 0.500
hsIFNγ (pg/mL)b 100 45.4 (25.4, 61) 94.4 38.4 (18.2, 78.8) 4.1 (-42, 40) 0.927 0.68 0.003
hsTNFα (pg/mL)b 100 10.7 (9.6, 13) 100 10.4 (8.6, 15) -6.9 (-26, 8.8) 0.196 0.71 0.001
sTNF-R1 (ng/mL)c 100 1.5 (1.4, 1.8) 100 1.6 (1.1, 2.0) -6.6 (-21, 14) 0.442 0.75 0.000
sTNF-R2 (ng/mL)c 100 1.4 (1.1, 1.8) 100 1.7 (1.2, 1.9) -5.0 (-12, 0.1) 0.009 0.94 0.000
Growth Factors            
EGFR (ng/mL)d 100 13.7 (12.6, 14.8) 100 18.1 (17.1, 20.2) -28 (-44, -18) 0.000 0.48 0.045
ErbB2 (ng/mL)d 100 3.6 (3.2, 4.1) 100 3.7 (3.1, 4.0) -6.8 (-9.4, -1.6) 0.142 0.72 0.001
hsGM-CSF (pg/mL)b 100 21.3 (17.4, 31.3) 94.4 28.7 (19, 53.4) -9.9 (-47, 8.1) 0.174 0.79 0.000
G-CSF (pg/mL)c 100 125 (99.6, 149) 100 91.4 (83, 123) 9.0 (-13, 34) 0.156 0.45 0.059
HGF (pg/mL)c 100 230 (205, 307) 100 380 (253, 687) -50 (-165, -20) 0.000 0.72 0.001
  1. Note: LLD = lower limit of detection
  2. a Limited to the biomarkers for which more than 70% of all the samples were detectable. Values were extrapolated below the standard curve for less than 14% of samples for hsIL-5, IFNα, and IL-6R, but were not extrapolated for any other markers included in the table. Sixteen markers are not included because more than 30% of samples were undetectable (IL-1β, IL-1RA, IL-5, IL-6, IL-17, VEGF), and/or a high percentage of the samples were extrapolated below the lowest point on the standard curve (IL-1α, IL-2, IL-7, IL-8, IL-10, IL-13, IL-15, TNFα, EGF, bFGF).b Kits from Linco/Milliporec Kit from Biosource
  3. d Kit developed in-house