In a new study entitled “Neutrophil trails guide influenza-specific CD8+ T cells in the airways,” researchers uncovered a key mechanism mediated by neutrophils that guides immune system cells to the site of an injury or infection. Moreover, this mechanism is crucial for immune cells to function properly once at the injury site. These findings are particularly relevant to the study of autoimmune diseases such as multiple sclerosis, since blocking immune cells from migrating and attacking healthy tissue may disrupt the progression of these diseases. The study was published in the journal Science.

Influenza virus (commonly refereed to as the flu virus) infects the layer of cells that line the respiratory tract. When infection occurs, cells of the immune system must be able to travel and reach the site of infection to eliminate the infected cells. Crucial players in the immune system for eliminating viruses are effector T cells. However, how these cells are guided and able to reach their final destination, either at the site of an injury or infection, is poorly understood.

In this new research, a team of scientists investigated how effector T cells are guided to the site of infection and discovered that this is achieved with the help of cells called neutrophils – a key player of the immune system and the first cells responding to infections. Neutrophils are the most abundant type of white blood cells of the immune system and are highly motile. The authors observed that neutrophils arrive rapidly (within one hour) to the site of infection and discovered that these migrating cells leave a long-lasting “trail” enriched in a chemokine, CXCL12. Chemokines are small protein molecules secreted by cells to “attract” other cells, in this case the effector T cells. When the team specifically removed the CXCL12 signaling, they discovered that T cells were unable to reach the site of infection so easily and that the ones who did were less efficient.

Minsoo Kim, Ph.D., study lead author and associate professor of Microbiology and Immunology at the School’s David H. Smith Center for Vaccine Biology and Immunology noted in a news release, “Immune cells team up and share information to get their job done, much like many types of animals take part in collective behaviors to benefit the group as a whole.”

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David J. Topham, Ph.D., co-author and the Marie Curran Wilson and Joseph Chamberlain Wilson Professor of Microbiology and Immunology added, “Understanding how immune cells collaborate to arrive at the site of an infection will lead to new ways to control and improve the body’s response to all types of illnesses.”

In multiple sclerosis and lupus, two autoimmune diseases, immune cells migrate and attack healthy tissue. These new findings may also underlie autoimmune disease pathogenesis, and so blocking neutrophil-mediated CXCL12 release may benefit multiple sclerosis and lupus patients.