The Immunology of Alpha-Gal Syndrome: History, Tick Bites, IgE, and Delayed Anaphylaxis to Mammalian Meat

The primary features of the alpha-gal syndrome (AGS) are (i) The IgE ab that are causally related to anaphylaxis with infusions of Cetuximab are specific for galactose alpha-1,3-galactose. (ii) In the USA, this IgE ab is induced by bites of the tick Amblyomma americanum. (iii) The anaphylactic reactions to food derived from non-primate mammals are delayed in onset by three to five hours. A further important fact is that all humans make a "natural" response to alpha-gal which includes IgM, IgG, and IgA, but not IgE. The clinical features of AGS are recognized in many parts of the world, but different species of ticks are involved. The immune response to tick bites includes T cells specific for tick protein, while IgE producing B cells appear to be derived from B cells specific for IgM or IgG. With repeated tick bites, the T cells develop a strong Th2 signal with IL-4 and IL-13 This obviously relates to IgE production, but may also be relevant to itching after tick bites which can last for weeks. The current hypothesis about the cause of the delayed reactions is based on the time that it takes to digest glycolipids from meat to LDL. The management of AGS symptoms is based on the avoidance of food derived from mammals; however, the only thing that can allow IgE to decrease is avoidance of tick bites.