Intestinal mast cell-derived leukotrienes mediate the anaphylactic response to ingested antigens

Anaphylaxis is a life-threatening complication of allergen exposure. While mechanisms governing anaphylaxis after intravenous injection have been defined in mice, these models neglect mucosal exposure that accompanies food ingestion. We investigated the role of mast cell populations within the intestine of mice in response to antigens delivered orally. Oral anaphylaxis required IgE-FcεR1 signaling, and profiling of intestinal mast cells revealed a rapidly developing population shaped by epithelial cues. Intestinal mast cells were largely epithelium-resident and displayed divergent transcriptomes and effector functions from connective tissue mast cells found throughout the body. Histamine synthesis was diminished and leukotriene generation enhanced. Mice genetically deficient in cysteinyl leukotriene synthesis, or those treated with aLOX5 antagonist, Zileuton, were protected from oral anaphylaxis whereas that elicited by intravenous injection was unaltered. BALB/cJ female mice were sensitized subcutaneously with OVAxAlum on d0 and d7 . Mice were challenged intragastrically with 20mg of OVA (Sigma grade III) in 200ul water on d14. MCs were sorted 24 hr later