Scientists dig into the mystery of unexplained allergic shock

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

* INCLUSION CRITERIA: * Subjects must be at least 13 years of age and no older than 75 years of age. * Subjects with IA must have a diagnosis of anaphylaxis occurring in the absence of an identifiable provoking agent or stimulus by a referral provider. Patient may carry both the diagnosis of 1A and the diagnosis of SA. * Subjects with SA must have a history of a severe reaction to a venom, food or, drug confirmed when possible by relevant skin testing, challenge testing, RAST, immunoCAP, or ELISA. within the past 36 months. * Subject must have had a doctor s office or ER visit, or a hospitalization for evaluation for anaphylaxis and have a history of involvement of the skin and/or mucosal tissue (e.g., flushing, itching, hives, angioedema, tongue swelling), and at least one of the following: * Respiratory compromise (e.g., dyspnea, hoarseness-laryngeal edema, wheeze-bronchospasm, stridor, reduced peak expiratory flow, hypoxemia). * Gastrointestinal symptoms of vomiting and/or diarrhea * Reduced blood pressure and/or associated symptoms of end-organ dysfunction (as evidenced hypotonia, hypoxia, collapse, syncope or incontinence). * Letter of referral from prospective study participant's referring physician, or similar primary provider - with copies of available medical evaluation and laboratory studies * Able and willing to consider a bone marrow biopsy and aspirate EXCLUSION CRITERIA: * Presence of conditions which in the judgment of the investigator or the referring physician may put the subject at undue risk for travel (including frequent episodes of IA not preventable by pre-medication, acute infection, severe thrombocytopenia \[minimum platelet count of 30,000\], or significant cardiovascular disease) * Any condition that - in the view of the principal investigator would make the subject unsuitable for enrollment in this study * Inability to provide informed consent * Pregnancy