Perivascular dendritic cells elicit anaphylaxis by relaying allergens to mast cells via microvesicles
Anaphylactic reactions are triggered when allergens enter the blood circulation and activate immunoglobulin E (IgE)–sensitized mast cells (MCs), causing systemic discharge of prestored proinflammatory mediators. As MCs are extravascular, how they perceive circulating allergens remains a conundrum. Here, we describe the existence of a CD301b+ perivascular dendritic cell (DC) subset that continuously samples blood and relays antigens to neighboring MCs, which vigorously degranulate and trigger anaphylaxis. DC antigen transfer involves the active discharge of surface-associated antigens on 0.5- to 1.0-micrometer microvesicles (MVs) generated by vacuolar protein sorting 4 (VPS4). Antigen sharing by DCs is not limited to MCs, as neighboring DCs also acquire antigen-bearing MVs. This capacity of DCs to distribute antigen-bearing MVs to various immune cells in the perivascular space potentiates inflammatory and immune responses to blood-borne antigens.
Source: ScienceNOW - Category: Science Authors: Choi, H. W., Suwanpradid, J., Kim, I. H., Staats, H. F., Haniffa, M., MacLeod, A. S., Abraham, S. N. Tags: Immunology, Online Only r-articles Source Type: news
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