Dynamic regulation of CD300b and CD300f on myeloid cells in oral immunotherapy

Oral immunotherapy (OIT) induces desensitization in IgE-mediated food allergy, yet the role of myeloid cells in acquisition of tolerance is unclear. CD300 receptors regulate activation of myeloid cells, with CD300f acting as an inhibitory receptor and CD300b as an activating receptor.

We sought to investigate whether the modulation of CD300 receptors on myeloid cells during OIT may reflect effector cell reprogramming and serve as biomarkers of treatment response.

Thirty-five patients undergoing OIT were prospectively enrolled. Peripheral blood was collected at baseline and during updosing; 19 patients completed sampling on reaching maintenance. CD300b and CD300f expression in eosinophils, monocytes, and neutrophils was analyzed by flow cytometry. Allergen-specific IgE and IgG4 levels were measured by ImmunoCAP. Associations with clinical parameters were assessed using logistic regression.

Baseline CD300b was higher in patients with lower starting doses (P ≤ .05). CD300f expression was lower in those with atopic dermatitis or multiple food allergies (P ≤ .03). A significant downregulation of CD300b expression in the surface of eosinophils, monocytes, and neutrophils was noted early in treatment (P ≤ .05). Longitudinally, the expression of CD300f increased on eosinophils, whereas the expression of CD300b decreased on the surface of monocytes and neutrophils. Specific IgE reduction correlated with downregulation of CD300b expression in monocytes (R = 0.51, P = .02) and higher CD300f expression in eosinophils (R = -0.45, P = .05).

Downregulation of CD300b and upregulation of CD300f during OIT suggests myeloid cell reprogramming toward a less inflammatory phenotype. These dynamic changes in expression suggest CD300b and CD300f as candidate biomarkers for understanding and monitoring OIT response.