Temperature change affects human health and asthma.[[1]] Serum IgE concentrations were shown to be significantly lower in experimental asthmatic mice treated at thermoneutral (30°C) than those treated at standard housing temperature (20°C).[3] A recent study found that the exosomes of mast cells (MC) can compete with MC to bind serum IgE and reduce asthma symptoms.[4] This study aimed to investigate whether temperature directly affects MC-derived exosomes in mediating the high-affinity receptor for IgE (Fc RI)-dependent MC activation and ovalbumin-induced asthma. In summary, this study provides evidence of the temperature-dependent regulation of MC-derived exosomes through regulation of Rab3a expression, which protected against Fc RI-dependent MC activation in vitro and experimental asthma in vivo. Temperature regulates Rab3a and mast cell-derived exosomal Fc RI to inhibit mast cell activation. [Extracted from the article]