The Influence of Oral Immunotherapy for Food Allergy on the Expression of CD300 Receptors on Myeloid Cells

Background: The CD300 receptor family consists of members with activating (CD300 b, c, e, f) and inhibitory (CD300 a, f) capabilities that are expressed on the surface of myeloid cells. Their regulation by Th2-associated cytokines suggests key roles during allergic inflammation. Whether oral immunotherapy (OIT) regulates the expression of CD300 receptors is currently unknown.

Objective: To characterize the expression of the CD300 family receptors on myeloid cells of food allergic patients undergoing OIT.

Methods: Patients undergoing OIT at the Shamir Medical Center were recruited prospectively. Blood was drawn before starting OIT, during up-dosing and after reaching maintenance. The expression of the different CD300 family members was analyzed by flow cytometry.

Results: Thirteen patients (median age of 12 years, 8 males) were recruited into the study. The most common allergen treated was sesame (n=5) and the median starting dose was 20mg of protein. The expression of the activating receptor CD300b decreased significantly from baseline to up-dosing on eosinophils, neutrophils and monocytes. The expression of CD300a, CD300c CD300e and CD300f did not change on myeloid cells following OIT. The expression of Siglec-8 on eosinophils, a receptor which enhances apoptosis, increased significantly compared to baseline.

Conclusions: The decrease in the expression of the activating receptor CD300b as well as the increase in the siglec-8 receptor on eosinophils suggest an inhibitory impact of OIT on myeloid cells. Whether these changes are part of an important mechanism mediating desensitization requires further investigation.