Increased HLA-DR expression on tissue eosinophils in eosinophilic esophagitis

Area of Science:

• Immunology
• Gastroenterology
• Cell Biology

Background:

• Eosinophilic esophagitis (EoE) is an allergic inflammatory disease of the esophagus.
• Human leukocyte antigen (HLA)-DR is a marker of immune cell activation.
• The role of HLA-DR expression on eosinophils in EoE is not well understood.

Purpose of the Study:

• To investigate whether eosinophils exhibit increased HLA-DR expression in patients with EoE compared to healthy controls (HC) and those with gastroesophageal reflux disease (GERD).

Main Methods:

• Biopsies and peripheral blood samples were collected from patients undergoing endoscopy for suspected EoE or GERD, along with HC.
• Immunohistochemistry was used to stain esophageal tissue for eosinophils (EG2) and HLA-DR.
• Flow cytometry analyzed peripheral blood eosinophil HLA-DR expression.

Main Results:

• Esophageal eosinophils showed significantly higher HLA-DR expression in EoE patients compared to GERD patients and HC (P < 0.01).
• No significant difference in HLA-DR expression was observed on peripheral blood eosinophils among the three groups (EoE, GERD, HC).
• Six participants were excluded due to insufficient eosinophils in tissue samples.

Conclusions:

• Eosinophils in the esophageal tissue of individuals with EoE demonstrate elevated HLA-DR expression.
• This increased expression suggests localized immune activation within the esophagus in EoE.
• HLA-DR expression on peripheral blood eosinophils does not appear to be a reliable marker for EoE.