Foreign proteins Insulin, seminal proteins, horse-derived antitoxins used to treat snake bites, etc. Complement Mediated Reactions Whole blood, serum, plasma, fractionated serum products, immunoglobulins, dextran Anaphylactic responses have been observed after the administration of whole blood or its products, including serum, plasma, fractionated serum products and immunoglobulins. One of the mechanisms responsible for these reactions is the formation of immune complexes resulting in the activation of the complement cascade. In addition, the anaphylatoxins may directly induce vascular permeability and contract smooth muscle. Individuals who are congenitally deficient for serum proteins may become sensitized to missing factors provided in blood products.
Cytotoxic reactions can also cause anaphylaxis, via complement activation.
This reaction causes agglutination and lysis of red blood cells and perturbation of mast cells, resulting in anaphylaxis. Iodinated contrast media may cause mast cell degranulation by their hyperosmolarity, and by activation of the complement and coagulation systems, but reactions also occur in subjects receiving the newer non-ionic contrast media. Narcotics Narcotics are recognized mast cell activators capable of causing elevated plasma histamine levels and anaphylactoid reactions. These are most commonly observed by anesthesiologists. Affected individuals tolerate choline or sodium salicylates, substances closely related structurally to aspirin, but different in that they lack the acetyl group found in aspirin.