Serum reactions. An analysis of commercial antivenoms and the possible role of anticomplementary activity in de-novo reactions to antivenoms and antitoxins.

Infusion of concentrated heterologous serum proteins may precipitate severe reactions in humans. Some of these reactions are not due to a preexisting hypersensitivity to the foreign protein, but rather to the strongly anticomplementary activity (ACA) of the infused protein. The latter mechanism could account for the occasional anaphylactoid reaction seen in a patient who has had no known previous exposure to the foreign protein. Similarly, it could account for the patient who fails to react to a preliminary subcutaneous trial dose, but then collapses when he is infused later with the same preparation. Nine commercial antivenoms from nine countries were examined and most were found to have high levels of anticomplementary activity. Considerable variation was found in both the immunochemical properties and the anticomplementary activity of these antivenoms. Antitoxins of equine origin to the toxins of diphtheria, tetanus and gas gangrene were also found to have high anticomplementary activity. Because of this activity these preparations should always be diluted and infused slowly. Lack of reaction to a test dose will never guarantee an uneventful infusion, and thus all infusions of heterologous immunoglobulin should be undertaken with the greatest caution and vigilance.