Peanuts can contribute to anaphylactic shock by activating complement.

Area of Science:

• Immunology
• Allergy Research

Background:

• Peanut allergy is a leading cause of fatal anaphylaxis, often persisting into adulthood.
• Key peanut allergen Ara h 1's resistance to digestion and dendritic cell activation contribute to its allergenicity.

Purpose of the Study:

• To investigate if peanut molecules can induce anaphylaxis through innate immune pathways.
• To elucidate the specific innate immune mechanisms underlying peanut-induced anaphylaxis.

Main Methods:

• Mice were treated to enhance sensitivity to vasoactive mediators and injected with peanut extract (PE).
• Shock was quantified using rectal thermometry.
• Gene-deficient mice and antagonists identified roles of complement, Fc receptors, cell types, and mediators in shock.

Main Results:

• Peanut extract induced dose-dependent shock in mice, activating complement in vivo and in vitro.
• Complement component C3a and Fc receptors were crucial for PE-induced shock.
• Macrophages and basophils, rather than mast cells, were key players, with platelet-activating factor and histamine as mediators.
• Shock occurred independently of the adaptive immune system, and LPS contamination was ruled out.

Conclusions:

• Peanuts can cause anaphylactic shock by stimulating C3a production.
• C3a activates macrophages, basophils, and mast cells, leading to the release of platelet-activating factor and histamine.
• This innate immune mechanism contributes to peanut-induced anaphylaxis.