Allergen challenge differentially affects the number of circulating monocyte subsets

Area of Science:

• Immunology
• Allergy and Clinical Immunology
• Respiratory Medicine

Background:

• Peripheral blood monocyte (PBM) subsets are crucial in inflammatory responses and tissue remodeling.
• Understanding PBM subset dynamics during allergen exposure is vital for allergic airway disease.

Purpose of the Study:

• To investigate the impact of Dermatophagoides pteronyssinus (Dp) allergen challenge on circulating PBM subsets in allergic patients.
• To correlate PBM subset changes with airway hyperresponsiveness (AHR) and inflammatory markers.

Main Methods:

• Flow cytometry was used to analyze PBM subsets (CD14, CD16, CCR4) in Dermatophagoides pteronyssinus-allergic patients (Dp-APs) and healthy controls (HCs) before and after allergen challenge.
• Plasma levels of CCL2, CX3CL1, and CCL17 were measured using ELISA.
• Patients were categorized into responders (Rs) with bronchoconstriction and non-responders (NRs) based on challenge outcomes.

Main Results:

• Baseline CD14++CD16+ PBMs were significantly higher in Dp-APs (Rs and NRs) compared to HCs and correlated negatively with AHR.
• Following allergen challenge, CD14++CD16+ PBMs decreased in Rs but not NRs, inversely correlating with plasma CCL17.
• Changes in CD14++CD16+ cells post-challenge correlated positively with AHR, and CCR4 expression was highest on these cells.

Conclusions:

• Expansion and subsequent mobilization of CD14++CD16+ monocytes after allergen challenge may contribute to AHR development in Dp-APs.
• The CD14++CD16+ monocyte subset, expressing CCR4, represents a potential therapeutic target in allergic airway inflammation.