Superallergens: a novel mechanism of IgE-mediated activation of human basophils and mast cells

• Published in: Clinical & experimental allergy reviews Vol. 4; no. s2; pp. 64 - 75
• Main Authors: Marone, G., Rossi, F. W., Bova, M., Detoraki, A., Liccardo, B., Petraroli, A.
• Format: Journal Article
• Language: English
• Published: Oxford, UK; Malden, USA Blackwell Science Ltd 01.12.2004
• Subjects: basophils; cysteinyl leukotriene C4; histamine; IL-13; IL-4; superallergens
• ISSN: 1472-9725; 1472-9733
• DOI: 10.1111/j.1472-9725.2004.00036.x

Summary Here we report that specific proteins induced in vivo by viruses (e.g. protein Fv), viral proteins (e.g. gp120) or bacterial proteins (e.g. protein L and protein A) can activate human mast cells and basophils (FcεRI+ cells) to release proinflammatory mediators and cytokines, thereby functioning as immunoglobulin superallergens. Protein Fv acts as an endogenous immunoglobulin superallergen by interacting with IgE VH3+. Similarly, gp120 of HIV‐1 is a viral superallergen activating FcεRI+ cells through interaction with IgE VH3+. Protein A of Staphylococcus aureus functions by interacting with IgE VH3+. Finally, Peptostreptococcus magnus, protein L and a fragment denoted B1–B4 induce mediator release from FcεRI+ cells through interaction with κ light chains of IgE bound on human FcεRI+ cells. Thus, we have identified a novel mechanism by which endogenous, bacterial and viral proteins specifically activate FcεRI+ cells, thereby acting as immunoglobulin superallergens. The in vivo implications of IgE‐mediated activation of human FcεRI+ cells by these immunoglobulin superallergens have yet to be defined. However, it is not inconceivable that endogenous, bacterial and viral superallergens play a pathophysiological role in certain forms of allergic reactions.