Identification of CCR9+ and CD103+ Dendritic Cells in Tolerance Protocols for Food Allergy

RATIONALE: CD103+ DCs (dendritic cells) and CCR9+ pDCs (plasmacytoid DCs) have been implicated in promoting tolerance through regulatory-T cell induction. We have conducted food oral immunotherapy (OIT) clinical studies over several years at Stanford University. We hypothesized that food allergy subjects have low CD103+ and CCR9+ expression on their DCs but that subjects undergoing food OIT would have increased DC expression of these markers compared to baseline values. METHODS: DCs expressing CD103 (integrin-alpha E) and CCR9 (CCL25 chemokine receptor) were examined in three cohorts-(1) OIT patients (n=8), (2) healthy controls (HC) (n=8), and (3) non OIT food allergy patients (FA) (n=8). PBMCs (peripheral blood mononuclear cells) were incubated for 6 hours either with or without stimulation by offending allergen. In addition, studies were performed to evaluate whether Treg function, Treg expression of Foxp3, and clinical outcomes correlated with DC subset changes. RESULTS: CD103+ and CCR9+ expression on DCs was significantly greater in HC versus FA patients (0.243% vs 0.073 %-CD103; p