Scientists at the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) have found that communication between two immune system cells can decrease allergic responses in mice. By studying the interactions between the two cells, the scientists hope to better understand the factors that contribute to allergic reactions, allergic asthma, and anaphylactic shock. The study appeared in a recent issue of the journal, Immunity .

Juan Rivera, Ph.D., acting chief of the NIAMS Laboratory of Immune Cell Signaling, in collaboration with researchers at the University of Udine in Italy , studied two seemingly unconnected immune system cells: T regulatory cells (Tregs) and mast cells. Tregs regulate the activity of other immune cells, especially the activity of other T cells, and help prevent autoimmunity, a condition in which the body's immune cells mistakenly attack its own tissues and vital organs. Mast cells play a role in inflammation and release histamine and other inflammatory factors that help fight off infections. Under certain circumstances, mast cells release excessive amounts of inflammatory factors, causing severe allergic reactions and, in some cases, anaphylactic shock, which can be deadly.

Dr. Rivera and colleagues showed that direct interaction between the two cells, in the form of cell surface to cell surface binding, suppressed the release of inflammatory factors from mast cells. Until this study, researchers were unaware of this mechanism for regulating allergic reactions. When the investigators discovered this mechanism, they considered the possibility that loss of this interaction may contribute to extreme allergic reactions. The researchers studied mice without Treg cells and found that they had increased allergic responses. In addition, the researchers removed the binding sites from the Tregs and mast cells in other mice and found that these mice also had increased allergic responses.

These findings may lead to a better understanding of why some people are more predisposed to allergic reactions, and possibly contribute to the development of therapies to counteract or prevent these conditions.

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Reference: Gri G, Piconese S, Frossi B, Manfroi V, Merluzzi S, Tripodo C, Viola A, Odom S, Rivera J, Colombo MP, Pucillo CE. CD4(+)CD25(+) Regulatory T Cells Suppress Mast Cell Degranulation and Allergic Responses through OX40-OX40L Interaction. Immunity. 2008 Nov;29(5):771-81.