Validity of multiplex-based assays for cytokine measurements in serum and plasma from non-diseased subjects: Comparison with ELISA

Multiplex-based immunoassays (MIA) allow the simultaneous measurement of different cytokines in small sample Volumes, but their applicability in samples from healthy subjects, as those participating in large-scale epidemiological studies is not well known. We compared measurements of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), interleukin-1 receptor antagonist (IL-1Ra), C-reactive protein (CRP) and soluble CD40L (sCD40L) obtained by MIA with those obtained by enzyme-linked immunosorbent assays (ELISA) in serum and plasma samples from 36 healthy subjects. We observed good correlations between measurements obtained by MIA and ELISA for IL-1Ra, CRP and sCD40L (r > 0.80) but poor correlations for IL-6, TNF-alpha and IL-1 beta (r < 0.40). When comparing MIA plasma and serum measurements, very high correlations were obtained for CRP (r = 0.98) and fairly good correlations for IL-1Ra (r = 0.60). In conclusion, multiplex-based assays can give an accurate estimate of the relative risk in large-scale epidemiological studies but only for cytokines that are present in relatively large concentrations (ng/mL). (C) 2009 Elsevier B.V. All rights reserved.