Table 2.
Correlation between EDTA plasma versus serum biomarkers measured by Luminex xMap™, clinical research study subjects a (n = 18 pairs)
| 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 |
Note: LLD = lower limit of detection
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
d Kit developed in-house