Long-Lasting Immune Cells in Lungs May Help To Defend Against Subsequent Viral Infection

A research team from the University of Basel has discovered immune cells living in the lungs that persist long after surviving the flu. Tests with mice showed that these helper cells improve the immune response against re-infection with another strain of flu virus. The discovery could provide approaches for longer-lasting vaccinations against rapidly changing viruses.

Even at the beginning of the corona pandemic, the question arose of how long the immunity lasts after a SARS-CoV-2 infection. The same question arises in the course of the Covid-19 vaccination. Immunological memory plays a decisive role in this - an interaction of immune cells, antibodies and signaling substances that allows the body to fight known pathogens particularly efficiently.

Researchers led by Prof. Dr. Carolyn King from the Department of Biomedicine at the University of Basel have now identified a group of immune cells in the lungs that are central to the defense against repeated infections with flu viruses. The same should apply to renewed infections with other pathogens causing respiratory diseases.

In experiments with mice, the researchers characterized a group of so-called T memory cells in the lung tissue that remain there for a long time after surviving the flu. The team reports on these so-called “T resident helper cells” in the journal “Science Immunology”.

Reservoir in the tissue

"There is still relatively little known about T-memory cells that remain in the tissue," explained Nivedya Swarnalekha, co-first author of the study. Previous studies focused in particular on the memory cells in the blood and lymph tissue. "It makes sense, however, that the body should create a reservoir of these cells in the tissue that was affected by the infection and where the same or similar pathogens could invade again."

In their study, the researchers describe two types of T helper cells in the lungs. One type releases signaling substances in the event of renewed infection in order to lend other immune cells “more deadly weapons” in the fight against the pathogen. The other type, which to date has only been characterized in lymph tissue but not in lung tissue, supports antibody-producing immune cells (B cells) and forms closely adjacent teams with them in the tissue.

In further experiments, the researchers were able to prove that the presence of these cells in close proximity to the antibody-producing B cells led to a more efficient immune response when a slightly different flu virus had to be fought off.

Approach for long-term effective vaccination protection

"These T-helper cells could be an interesting starting point for longer-lasting influenza vaccinations," said David Schreiner, also co-first author of the study. It is conceivable, for example, to supplement vaccines with active ingredients that support the formation of these T helper cells that migrate into the tissue. This would require further research and development.

Reference
Swarnalekha N, Schreiner D, Litzler LC, et al. T resident helper cells promote humoral responses in the lung. Science Immunology. 2021;6(55). doi:10.1126/sciimmunol.abb6808

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