Involvement of the mannose receptor in the uptake of Der p 1, a major mite allergen, by human dendritic cells

Background: Immature dendritic cells (DCs) take up antigens in peripheral tissues and, after antigen processing, mature to efficiently stimulate T cells in secondary lymph nodes. In allergic airway diseases DCs have been shown to be involved in the induction and maintenance of a T(H)2-type profile. Objective: The present study was undertaken to determine pathways of Der p 1 (a house dust mite allergen) uptake by human DCs and to compare Der p I uptake between DCs from patients with house dust mite allergy and DCs from healthy donors. Methods: Monocyte-derived DCs (MD-DCs) were obtained from patients with house dust mite allergy (n = 13) and healthy donors (n = 11). Der p 1 was labeled with rhodamine. Der p 1 uptake by MD-DCs was analyzed by means of flow cytometry and confocal microscopy. Results: Rhodamine-labeled Der p I was demonstrated to be taken up by MD-DCs in a dose-, time-, and temperature-dependent manner. The involvement of the mannose receptor (MR) in the Der p I uptake was demonstrated by using (1) inhibitors of the MR-mediated endocytosis (mannan and blocking anti-MR mAb), which inhibited the Der p I uptake from 40% to 50%, and (2) confocal microscopy showing the colocalization of rhodamine-labeled Der p 1 with FITC-dextran. Interestingly, compared with DCs from healthy donors, DCs from allergic patients expressed more MR and were more efficient in Der p 1 uptake. Conclusion: These results suggest that the MR could play a key role in the Der p 1 allergen uptake by DCs and in the pathogenesis of allergic diseases in dust mite-sensitive patients.