The Peripheral Blood Eosinophil Proteome

A system-wide
understanding of biological processes requires a
comprehensive knowledge of the proteins in the biological system.
The eosinophil is a type of granulocytic leukocyte specified early
in hematopoietic differentiation that participates in barrier defense,
innate immunity, and allergic disease. The proteome of the eosinophil
is largely unannotated with under 500 proteins identified. We now
report a map of the nonstimulated peripheral blood eosinophil proteome
assembled using two-dimensional liquid chromatography coupled with
high-resolution mass spectrometry. Our analysis yielded 100,892 unique
peptides mapping to 7,086 protein groups representing 6,813 genes
as well as 4,802 site-specific phosphorylation events. We account
for the contribution of platelets that routinely contaminate purified
eosinophils and report the variability in the eosinophil proteome
among five individuals and proteomic changes accompanying acute activation
of eosinophils by interleukin-5. Our deep coverage and quantitative
analyses fill an important gap in the existing maps of the human proteome
and will enable the strategic use of proteomics to study eosinophils
in human diseases.