The purpose of this study is to explore different mechanisms for anaphylaxis and find novel biomarkers for this hypersensitivity syndrome. The study participants are patients with anaphylaxis, patients with mild allergic reactions, and patients with febrile transfusion reactions. The investigators will also include a group of healthy controls.

Inclusion Criteria:

According to the specific cohort:

1. Diagnosis of anaphylaxis
2. Mild allergic reaction
3. Febrile transfusion reaction
4. Healthy, no known allergic disease

Exclusion Criteria:

Suspicion or diagnosed sepsis Children

Adults