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The Two Faces of Immune Cells

Dubbed the “Jekyll and Hyde” properties, scientists at Trinity College Dublin identified a rare, new cell in the immune system that is able to express two forms of T cells.

The immune system functions to control infection, utilising various immune cells, such as T cells to respond to and control invading microbes. However, if these immune cells are not highly regulated, they can attack and damage body tissues, leading to the development of autoimmune diseases.

Research findings by a team led by Kingston Mills, Professor of Experimental Immunology, and Dr Sarah Edwards and Dr Caroline Sutton, Postdoctoral Fellows in the School of Biochemistry and Immunology in the Trinity Biomedical Sciences Institute were published on the Journal of Experimental Medicine.

Their findings could provide information for designing more effective vaccines to prevent infections such as MRSA and assist development of therapies for autoimmune diseases such as multiple sclerosis or rheumatoid arthritis.

Molecules on T cells called T cell receptors (TCRs) allow the cells to recognise specific infectious agents. There are two types of TCRs, ‘αβ’ or ‘γδ’, for which αβs are the most common in the body. This type of T cells play an important from in remembering prior infection or immunisation, protecting us against re-infection and medicate vaccine-induced protective immunity. γδ TCRs are more common on mucosal surfaces, such as the lung or gut, providing a first line of defence against pathogens.

The research team discovered a new cell type which is able to express both αβ and γδ TCRs. This rare hybrid also displays the properties of both αβ and γδ T cells.

Using a model of Staphylococcus aureus infection, Professor Mills and his team found that these cells are rapidly mobilised during infection and play a key role in quickly eliminating the microbes from the body.

The induction of these hybrid αβ-γδ T cells may thus represent a novel approach in the design of more effective vaccines against Staph aureus and other infectious diseases, while advancing our ability to control their response may yield additional therapeutic options.

Professor Mills added, “In a model of autoimmune disease, we found that the hybrid T cells can also trigger the inflammatory cascade that mediates tissue damage in autoimmunity. Therefore, approaches for inhibiting these highly activated immune cells in susceptible individuals may open up new approaches for the treatment of autoimmune diseases such as psoriasis and multiple sclerosis.” [APBN]