Harvard Researchers Uncover Insight into T Cells and Autoimmune Disease

Harvard Medical School, courtesy of ThePhotosite/Shutterstock

Researchers from Harvard Medical School have published insight in Science Daily about how T cells function in autoimmune diseases. The researchers investigated the thymus, a small gland that is part of the immune system, to understand how T cells learn to identify foreign invaders like viruses and bacteria.

Autoimmune diseases are complex immunological conditions in which the body’s immune system targets its own cells and tissues. Although the reasons autoimmune diseases occur on a cellular level are still unclear, researchers believe that the diseases are caused by a combination of factors, including genetics, environment and previous infections. Systemic lupus, rheumatoid arthritis and Crohn’s disease are just a handful of autoimmune conditions that can occur when the immune system begins attacking the body, causing widespread inflammation and damage to organs that can be life-threatening and permanent.

Autoimmune diseases affect an estimated 23.5 million Americans, and while there are treatments, many of them do not target the origins of the disease, making the conditions chronic and life-long diagnoses. Now, Harvard researchers are getting one step closer to understanding why these diseases occur on a cellular level.

"Our immune system is super powerful. It can kill any cell in our body, it can control any pathogen we encounter, but with that power comes great responsibility," Daniel Michelson, an M.D./Ph.D. student at Harvard Medical School and the first author of the study wrote. "If that power is left unchecked, it can be lethal. In some autoimmune diseases, it is lethal."

The research group was interested in understanding how the immune system determines what types of cells are meant to be in the body and which are to be considered enemies, designated for destruction. The work began by taking a closer look at the thymus gland, which houses newborn T cells and educates them.

The thymus previously intrigued biologists in the 1800s when they recognized cells that were seemingly out of place in the gland, such as cells that looked like they came from muscles, intestines and skin, even though the thymus itself was not part of any of those groups.

Harvard researchers found that the thymus mimics different tissues throughout the body in order to educate nascent immune cells to understand that these types of proteins are friendly. During the education process, T cells that mistakenly react against friendly tissues either receive a command to self-destruct or are repurposed into other types of T cells that are not meant to attack. The thymus is responsible for getting rid of potentially autoreactive T cells, which are drivers of autoimmune disease.

Of course, this system doesn’t always work, as we know that autoimmune diseases are very prevalent. The next steps in the research process are to understand how these mimetic cells in the thymus play a role in autoimmune diseases and explore how mimetic cell types, T cell function and dysfunction occur within the thymus. The work could potentially uncover the mysterious origins of autoimmune diseases, leading to eventual treatment.