Development of an ultra-sensitive single molecule counting assay for the detection of interleukin-13 as a marker for asthmatic severity.
OBJECTIVE
Interleukin-13 (IL-13) has been difficult to quantify within human serum due to low abundance. Available assays have not been sensitive enough to detect IL-13 at the femtogram level. Thus, there are inconsistencies within the published literature as to IL-13 concentrations in normal or disease populations. To better understand IL-13 serum concentrations, a highly sensitive immunoassay was developed and used to determine concentrations from asthmatics with varying clinical severities.


METHODS
A single molecule counting (SMC) method was used to analyze serum samples from a total of 145 individuals (60 severe asthma, 60 moderate asthma, 60 mild asthma and 23 healthy donors).


RESULTS
IL-13 concentrations correlated with severity of asthma, with overlapping ranges. Mean IL-13 levels were highest in severe asthma. Mean IL-13 levels in moderate asthma population were second highest followed by mild asthma with the lowest IL-13 concentration. IL-13 concentrations in healthy donors were similar to the mild asthmatic population. The average concentrations of IL-13 in severe, moderate, mild and healthy donors were 1.286pg/mL, 0.672pg/mL, 0.508pg/mL and 0.155pg/mL respectively.


CONCLUSIONS
Severe asthma patients have elevated levels of IL-13.
Clinical Immunology, GlaxoSmithKline, King of Prussia, PA 19406, United States. Electronic address: boyenoh.x.gaye@gsk.com.
Boyenoh
B
Gaye
Clinical Immunology, GlaxoSmithKline, King of Prussia, PA 19406, United States.
Dan
D
Sikkema
Clinical Immunology, GlaxoSmithKline, King of Prussia, PA 19406, United States.
Thomas N
TN
Lee
D001249:Asthma / Q000097:blood* / Q000175:diagnosis / Q000276:immunology; D015415:Biomarkers / Q000097:blood; D005260:Female; D006801:Humans; D007118:Immunoassay; D018793:Interleukin-13 / Q000097:blood*; D008297:Male; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index
D015415:Biomarkers; C578095:IL13 protein, human; D018793:Interleukin-13
Asthma; Cytokine; IL-13