Biomarkers of eosinophil involvement in allergic and eosinophilic diseases: review of phenotypic and serum markers including a novel assay to quantify levels of soluble Siglec-8.
There remains considerable controversy in the management of eosinophilic disorders, mainly due to a paucity of information regarding the clinical interpretation of total blood eosinophil counts versus surface activation markers versus eosinophil-derived or eosinophil-influencing mediator levels. Regrettably, few tests have been validated that define a unique clinical or prognostic phenotype that is more useful than simply monitoring total blood eosinophil counts. In this manuscript, phenotypic (cell surface) markers, along with serum and tissue-based markers that have been examined in the context of disease activity, are reviewed. We also report the development of a novel assay for detecting soluble Siglec-8 (sSiglec-8), a protein likely derived largely from eosinophils, as a potential serum biomarker. The assay consists of a competitive ELISA using a recombinant Siglec-8-Fc fusion protein. The goal of this preliminary study was to determine if sSiglec-8 is a useful biomarker that differentiates among patients with various eosinophil-associated diseases. In the final analysis, it is fair to say that further research is sorely needed to fully understand and validate the utility of various biomarkers, including sSiglec-8, before their use in clinical practice can be recommended with confidence.
Department of Medicine, Division of Allergy and Clinical Immunology, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
Ho Jeong
HJ
Na
Robert G
RG
Hamilton
Amy D
AD
Klion
Bruce S
BS
Bochner
D015703:Antigens, CD / Q000097:blood*; D000944:Antigens, Differentiation, B-Lymphocyte / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D002469:Cell Separation; D003937:Diagnosis, Differential; D004797:Enzyme-Linked Immunosorbent Assay; D004802:Eosinophilia / Q000097:blood / Q000175:diagnosis* / Q000276:immunology; D004804:Eosinophils / Q000276:immunology*; D006801:Humans; D006967:Hypersensitivity / Q000097:blood / Q000175:diagnosis* / Q000276:immunology; D037102:Lectins / Q000097:blood*; D008396:Maryland; D010641:Phenotype; D011237:Predictive Value of Tests; D015203:Reproducibility of Results
D015703:Antigens, CD; D000944:Antigens, Differentiation, B-Lymphocyte; D015415:Biomarkers; D037102:Lectins; C403967:SIGLEC8 protein, human