Mast cell desensitization inhibits calcium flux and aberrantly remodels actin
W.X. Gladys Ang, … , A. Wesley Burks, Soman N. Abraham
W.X. Gladys Ang, … , A. Wesley Burks, Soman N. Abraham
Published September 26, 2016
Citation Information: J Clin Invest. 2016;126(11):4103-4118. https://doi.org/10.1172/JCI87492.
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Research Article Immunology

Mast cell desensitization inhibits calcium flux and aberrantly remodels actin

Abstract

Rush desensitization (DS) is a widely used and effective clinical strategy for the rapid inhibition of IgE-mediated anaphylactic responses. However, the cellular targets and underlying mechanisms behind this process remain unclear. Recent studies have implicated mast cells (MCs) as the primary target cells for DS. Here, we developed a murine model of passive anaphylaxis with demonstrated MC involvement and an in vitro assay to evaluate the effect of DS on MCs. In contrast with previous reports, we determined that functional IgE remains on the cell surface of desensitized MCs following DS. Despite notable reductions in MC degranulation following DS, the high-affinity IgE receptor FcεRI was still capable of transducing signals in desensitized MCs. Additionally, we found that displacement of the actin cytoskeleton and its continued association with FcεRI impede the capacity of desensitized MCs to evoke the calcium response that is essential for MC degranulation. Together, these findings suggest that reduced degranulation responses in desensitized MCs arise from aberrant actin remodeling, providing insights that may lead to improvement of DS treatments for anaphylactic responses.

Authors

W.X. Gladys Ang, Alison M. Church, Mike Kulis, Hae Woong Choi, A. Wesley Burks, Soman N. Abraham

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Figure 7

Antigen specificity of desensitization.

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Antigen specificity of desensitization. (A) RBL-2H3 cells were sensitize...
(A) RBL-2H3 cells were sensitized with a 1:5 ratio of anti-DNP to anti-OVA IgE, then desensitized to DNP-HSA or OVA before challenge with DNP-HSA (10 ng/ml) or OVA (1 μg/ml). Data were analyzed via 1-way ANOVA and are representative of at least 3 independent experiments. (B and C) 107 BMMCs per sample were sensitized with biotinylated IgE, then challenged with Ag for the indicated times. Lysates were immunoprecipitated with streptavidin beads and blotted for β-actin and FcεRIγ. (D) 107 BMMCs per sample were sensitized with a mixture of biotinylated and unbiotinylated IgE, then desensitized or challenged with Ag for the same amount of time (~2 hours). Lysates were then immunoprecipitated with streptavidin beads and blotted for β-actin and FcεRIγ. Data represent SEM. ***P < 0.001.