The levels of two molecules in the blood — eosinophil cationic protein (ECP) and interleukin-5 (IL-5) — reflect eosinophil activation in patients with eosinophilic granulomatosis with polyangiitis (EGPA), a study shows.
As a result, these molecules may be used as markers to determine disease activity in EGPA patients and distinguish between those with active disease and patients in remission.
The study, “Usefulness Of Biomarkers Of Eosinophil Activation In Monitoring Egpa Disease Activity,” was recently presented at the 19th International Vasculitis and ANCA Workshop in Philadelphia.
Eosinophils are a type of immune cells that play a central role in EGPA development. Researchers hypothesize that the degree of eosinophilic activation, measured through levels of ECP and the inflammatory molecule IL-5, could serve as a biomarker for EGPA, in addition to blood eosinophil count (the total number of eosinophils in blood).
However, existing studies have shown inconsistent results regarding the use of these markers in clinical practice. TO address this, researchers in this study sought to evaluate the usefulness of ECP and IL-5 as markers of disease activity in EGPA.
They collected 53 samples of serum (a component of the blood) from 37 patients with EGPA and examined the samples for blood eosinophil count, and levels of ECP and IL-5. These markers were then compared to the patients’ Birmingham vasculitis activity score (BVAS), an established measure of disease activity.
Among the 53 samples, 17 were collected from patients in remission (a BVAS score of zero), while the remaining were from patients with varying levels of disease activity.
The team found that EGPA patients with active disease had significantly higher levels of blood eosinophils, ECP, and IL-5 than patients in remission.
Additionally, BVAS scores were moderately correlated with blood eosinophil count, serum ECP, and IL-5, in that the higher the disease activity, the more likely a patient was to have a high blood eosinophil count, ECP, and IL-5.
Contrary to blood eosinophil counts, levels of ECP and IL-5 could also distinguish patients in remission from those with low disease activity, the latter of whom also had significantly higher levels of these molecules.
“Serum ECP and IL-5 reflect the degree of eosinophilic activation and might represent useful biomarkers in EGPA, complementary to blood eosinophilia, especially in patients with low disease activity or grumbling disease,” the researchers wrote.