Editors' ChoiceImmunology

Fishing for Allergic Antibodies

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Science Translational Medicine  23 Jan 2013:
Vol. 5, Issue 169, pp. 169ec18
DOI: 10.1126/scitranslmed.3005695

Anaphylaxis is a rapid onset and severe type of allergic reaction mediated by anti-allergen immunoglobulin E (IgE) antibodies. IgE somehow relocates to the dermal cell surface, working together with mast cells to elicit an allergic response. IgE acquisition was previously assumed to be a passive diffusion process, but a new study by Cheng et al. shows differently. Mast cells apparently troll the blood, fishing for IgE using vascular cellular projections and pulling it to the surface.

Cheng and colleagues compared mouse mast cells from dermal and peritoneal tissues and observed that the cells acquired new IgE differently. Peritoneal mast cells uniformly bound new IgE, whereas only a subset of dermal cells bound IgE in the skin. Speculating that this was not passive IgE uptake in the skin, the researchers imaged dermal mast cells using a fluorescently labeled reporter IgE. Dermal perivascular mast cells were more likely to acquire IgE than were mast cells further away from the blood vessels. Similarly an anti–mast cell fluorescent antibody, which was confined to the intravascular space, stained only a subset of tissue cells. Interestingly, images from static mouse tissue sections demonstrated mast cell protrusions within the lumen of the blood vessels. Cheng et al. then used real-time intravital confocal microscopy to confirm that these protrusions represented tissue mast cells reaching across the blood vessel wall into the circulation to acquire intravenously injected IgE. Some cells continuously trolled the blood, whereas others cast and retracted their vascular projections.

This finding opens up new avenues for investigating the role that mast cells play in bloodborne processes such as host defense, hemostasis, and inflammation. Furthermore, it suggests that there are diverse types of mast cells carrying out specific functions, which has implications for developing targeted allergy therapeutics. Nevertheless, the authors’ findings describe mast cell behavior in mice and will require further studies to confirm these phenomena in human skin and allergic reaction.

L. E. Cheng et al., Perivascular mast cells dynamically probe cutaneous blood vessels to capture immunoglobulin E. Immunity 38, 1–10 (2013). [ABSTRACT]

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