Immunity: Allergic reactions help fight bacterial infections.

September 11, 2020 // --- Allergic reactions are one of the most common diseases in Europe, with an estimated 150 million Europeans experience repeated allergic reactions, a proportion that could increase to half of the entire European population by 2025.
people with allergic reactions initially experience "allergenicity," which means that their immune system develops a specific class of antibodies, called immunoglobulin E antibodies (IgE), that identify external proteins called allergens.
IgE binds to cells that express a specific subject, Fc-R1.
only a few cell types in the body that express Fc'R1 receptors, and the most important cells may be fat cells, an immune cell found in most tissues throughout the body.
(Photo source: www.pixabay.com) When exposed to allergens again, fat cells (IgE in combination with their Fc?R1 subjects) react immediately by rapidly releasing different media (such as histamines, proteases, or cytokines) that cause symptoms of classic allergic reactions.
these symptoms depend on the tissue that is in contact with the allergen and range from sneezing/wheezing (respiratory tract) to diarrhea and abdominal pain (gastrointestinal) or itching (skin).
whole body contact allergens can activate a large number of fat cells from different organs at the same time, causing systemic allergic reactions.
despite decades of research and a thorough understanding of the key role of IgE and fat cells in allergies, the physiological mechanisms behind this "allergy phenomenon" are not fully understood.
2006, Stephen J. Galli and his lab at Stanford University revealed the importance of fat cells for innate resistance to certain snake venoms and bees.
by Galli's lab showed that "allergic reactions" played a key role in the defense of accessive hosts against high doses of venom.
following the discovery, Philipp Starkl, a senior postdoctoral fellow at the Medical University of Vienna and CeMM, Sylvia Knapp, a professor at the Medical University of Vienna and CeMM PI, and Stephen J. Galli of Stanford University School of Medicine, and colleagues looked at whether the phenomenon could be linked to the defense of other toxin-producing organisms, especially pathogenic bacteria.
the authors chose Staphylococcus agenic model because of its great clinical significance and extensive toxin library.
the bacteria is a prototype antibiotic-resistant pathogen and has been linked to the development of allergic immune responses in diseases such as asthma and endexual dermatitis.
found that mice with mild Staphylococcus austratic skin infections produced adaptive immune responses and specific IgE antibodies to bacterial components.
when these mice face severe secondary lung or skin and soft tissue infections, this immune response makes them more resistant.
, however, this protection could not be established in mice lacking functional IgE effect sub-mechanisms or fat cells.
findings suggest that the "allergic" immune response to bacteria is not pathological, but protective.
, defending against toxin-producing pathogenic bacteria may be an important biological function of allergy modules.
(bioon.com) Source: Allergic immune responses help fighting bleds original source: Philipp Starkl et al, IgE Effector Mechanisms, in Concert with Mast Cells, Contribute to Acquired Host Defense against Staphylococcus aureus, Immunity (2020). DOI: 10.1016/j.immuni.2020.08.002.