Human dendritic cells in the severe combined immunodeficiency mouse model:Their potentiating role in the allergic reaction

Dendritic cells (DCs) are present in the lungs and airways of healthy and a llergic subjects where they are exposed to inhaled antigens. After the upta ke of antigens, DCs migrate to lymphoid organs where T cells initiate and c ontrol the immune response. The migratory properties of DCs are an essentia l component of their function but remain unclear in the situation of allerg ic diseases. To better understand the role of DCs in response to allergens, we first investigated their presence in an original experimental model of allergic asthma: the humanized severe combined immunodeficiency (SCID) mous e reconstituted with peripheral blood mononuclear cells from patients sensi tive to Dermatophagoides pteronyssinus (Dpt). Human DCs were detected in lu ngs of mice developing an inflammatory pulmonary infiltrate and appeared to be mainly located in the alveolar spaces. In a second step, human DCs were generated in vitro from monocytes and injected into naive SCID mice expose d or not exposed to Dpt aerosols. Their migratory behavior was explored, as well as their potential role in modulating the IgE production after exposu re to Dpt. After exposure to Dpt, the number of DCs present in airways decr eased, while it increased into the spleen and thymus of the mice. The IgE p roduction increased in the presence of DCs as compared with mice not inject ed with DCs. These results suggest that DCs may play a role in the pulmonar y allergic reaction developed in response to Dpt in SCID mice.