Pediatric reference ranges for proinflammatory and anti-inflammatory cytokines in cerebrospinal fluid and serum by multiplexed immunoassay

Abstract

To define cytokine concentrations and detectability in children with noninflammatory neurological disorders (NIND). The multiplex bead assay technology was used for simultaneous measurement of 34 soluble cytokines/chemokines in cerebrospinal fluid (CSF) from 73 NIND. Sera from 36 healthy children and 37 NIND also were analyzed. In CSF, CXCL10 had the highest concentration; CCL2, CXCL10, and interleukin (IL)-6 were detectable in all samples, and CXCL8, CCL22, CXCL1, IL-16, and IL-1 receptor antagonist were found in ≥50% of the samples. In serum, CXCL1 had the highest concentration; sIL-2Ra, CXCL1, CXCL10, and CCL22 were detectable in all samples, and CCL2, IL-12, CCL5, and granulocyte monocyte colony-stimulating factor (GM-CSF) were found in ≥50% of the samples. The mean CSF:serum ratio for CCL2 was several-fold higher than the rest, with the CXCL10 and CXCL8 ratios also >1. Intercorrelations between CSF cytokines included CCL2 versus CXCL8 and IL-6, and CXCL1 versus CCL22, reflecting both T-helper-1 (Th1)/Th1 and Th1/Th2 relations. Serum correlations included CCL11 versus CCL2, GM-CSF, and IL-4. For serum cytokines, the agreement between healthy children and NIND was good, with the exception of higher CCL4 in NIND. Cytokines in children varied greatly in concentration and detectability, with chemokines predominating in the CSF. These data allow investigators to select their own kit cytokines, instead of manufacturer-selected cytokines, for greater cost-effectiveness and interpretability.

Figures

FIG. 1.

Cytokine concentrations in (A) cerebrospinal fluid (CSF) and (B) serum. Means with standard deviation (SD) in parentheses (larger figure) and medians with interquartile range in parentheses (insert) are ranked. Other medians could not be calculated due to the number of samples with undetectable levels.

FIG. 2.

Cytokine detection rates in CSF and serum in the entire dataset. Percent detectability was defined as the percentage of samples in which a given cytokine could be detected. The order of the cytokines displayed is from the highest to lowest CSF detection rate.

FIG. 3.

Comparison of mean serum cytokine concentrations in healthy controls versus neurological controls (NIND). Statistical significance by t-tests is indicated. Except for CCL4, nothing remained significant after Bonferroni corrections, or after exclusion of undetectable levels. The two P-values for CCL4 are for analysis with and without undetectable values.