IgE levels may offer important clues to disease patterns seen in EGPA
Study shows IgE may be tied to skin vasculitis and heart problems
In people with eosinophilic granulomatosis with polyangiitis (EGPA), those with skin or heart involvement have significantly higher blood levels of immunoglobulin E (IgE), a type of natural antibody frequently linked to EGPA, a study showed.
Testing positive for the self-reactive antibodies ANCAs against the myeloperoxidase (MPO) protein tended to be linked to a higher likelihood of glomerulonephritis — an inflammatory kidney disease — and to inflammation of medium-sized arteries in the head and abdomen. Arteries are blood vessels that carry oxygen-rich blood away from the heart and into the rest of the body.
The findings suggest that IgE levels may be associated with the development of specific complications in EGPA, such as skin vasculitis and cardiomyopathy, while MPO-ANCA positivity may be linked to inflammation in medium-sized arteries. However, the researchers noted that “further research is required to conclude the association between MPO-ANCA and medium-sized [vasculitis] in EGPA.”
The study, “Clinical value of biomarkers in relation to artery size in eosinophilic granulomatosis with polyangiitis: findings from an inception cohort at a Japanese City Hospital,” was published in Clinical Rheumatology.
Understanding EGPA and the blood vessels it can affect
EGPA is a rare type of ANCA-associated vasculitis (AAV), a group of autoimmune diseases marked by inflammation and damage in small blood vessels, and less commonly, medium-sized arteries.
Most cases are caused by self-reactive antibodies called ANCAs, which most often target either MPO or a protein called proteinase 3.
The rare form of AAV is marked by granulomas — clumps of immune cells primarily made up of eosinophils. People with the disease develop lesions in small arteries, such as those in the skin, but medium-sized arteries that supply the digestive tract and brain can also be affected.
Here, a trio of researchers at Hiroshima Citizens Hospital in Japan set out to investigate potential associations between disease biomarkers and the size of affected arteries, including medium-sized arteries, in people with EGPA.
They retrospectively analyzed data from 30 people diagnosed with EGPA between April 2012 and December 2024 at their hospital. The biomarkers evaluated included eosinophils, IgE, anti-MPO ANCAs, and rheumatoid factor (RF), another self-reactive antibody.
What the researchers found in the patient group
Skin vasculitis and glomerulonephritis, or inflammation of the kidney’s filtering units, were classified as small vessel vasculitis. Medium-sized vasculitis was considered to involve head and abdominal arteries. Cardiomyopathy was analyzed as an additional outcome.
Results showed that all participants had elevated eosinophil counts. RF levels were elevated in 29 of 30 people, and IgE levels were elevated in all 26 patients with available data. Also, 40% had ANCAs against MPO.
One third of patients had skin vasculitis, 16.7% had glomerulonephritis, and 16.7% had medium-sized vasculitis. Cardiomyopathy occurred in 13.3% of patients, and all of these cases were in the MPO-ANCA-negative group.
Among the five patients with medium-size arterial involvement, two had signs of blood flow blockage, and cell death, in a part of the brain, while another had enlarged arteries in the temples with eosinophil-rich inflammation.
Another person had abdominal bleeding with several arteries showing bulging, weakened areas. The remaining patient had brain bleeding and inflammation of a medium-sized artery in the gallbladder, which is part of the digestive system.
Statistical analyses showed that IgE levels were significantly higher in people with skin vasculitis (3,620 vs. 1,000 international units/mL) or cardiomyopathy (4,065 vs. 1,205 international units/mL), compared with those without these complications.
IgE cut-off levels show potential diagnostic value
A cut-off IgE level of 1,860 international units/mL could distinguish patients with skin vasculitis from those without with an accuracy of 82%. A cut-off IgE level of 2,465 international units/mL was able to distinguish patients with cardiomyopathy from those without with an accuracy of 84%.
A greater proportion of people with medium-sized vasculitis tested positive for anti-MPO-ANCAs than those without this complication (80% vs. 32%). These antibodies were also more common in people with glomerulonephritis. However, these differences failed to reach statistical significance.
Medium-size arterial inflammation “tended to be associated with MPO-ANCA positivity,” the researchers wrote, adding that future studies are needed to confirm this potential link.
“In conclusion, elevated IgE levels were correlated with both cutaneous vasculitis and cardiomyopathy in an inception [group of EGPA patients] in Japan,” the team wrote. “Further studies with larger [patient groups] are needed to confirm these findings, as our results are based on a retrospective study with a small sample size.”
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