Writing to a European audience, Starkl et al note that not only do 150 million Europeans now suffer from some type of allergy, but by 2025 over half of Europe will have allergies if current trends hold true. Many would initially blame the IgE antibody and allergic cells like mast cells for this medical malady and consider this arm of the immune system to be a bad guy. Sure, they help fight parasites, but otherwise they seem to cause a lot of harm outside that benefit. In this study, however, researchers uncovered a previously unrecognized function for IgE and mast cells in fighting severe bacterial infections related to Staphylococcus aureus.
Collaborating with other researchers, Starkl examined whether IgE and mast cells might play a role in fighting bacterial infections starting with staphylococcus, which causes many deadly infections. They knew that this bacteria also played a role in developing immune responses in asthma and eczema, so they started with it.
In a mouse model, they found that Staphylococcus aureus infections triggered not only the expected antibody response but also specific IgE antibodies. This appeared to help the mice fight later staphylococcus infections in deeper tissues. When the mice were unable to make the IgE, they had higher levels of more severe secondary infections.
Rather than being bad guys, IgE and mast cells clearly contribute to our immune defenses against bacteria. This is not surprising as mast cells are found throughout our body where a barrier exists between the outside and the inside. Our sinuses, our skin, our GI tract, and even our blood-brain barrier possess mast cells which have been shown in other studies to coordinate the immune system when microbes attack.
Philipp Starkl, Martin L. Watzenboeck, Lauren M. Popov, Sophie Zahalka, Anastasiya Hladik, Karin Lakovits, Mariem Radhouani, Arvand Haschemi, Thomas Marichal, Laurent L. Reber, Nicolas Gaudenzio, Riccardo Sibilano, Lukas Stulik, Frédéric Fontaine, André C. Mueller, Manuel R. Amieva, Stephen J. Galli, Sylvia Knapp. 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
Thanks to Science Daily:
CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences. “Allergic immune responses help fight bacterial infections.” ScienceDaily. ScienceDaily, 9 September 2020. <www.sciencedaily.com/releases/2020/09/200909114814.htm>.