Fall. A season marked by bright orange foliage, the triumphant return of pumpkin spice lattes, and the inevitable start of the annual flu season. For many of us, catching the flu is an unpleasant but ultimately non-life-threatening experience. Indeed, the human immune system has evolved to become highly effective at protecting us from lasting damage by viruses, bacteria, parasites and even tumors, correctly targeting only foreign pathogens or sick cells. But how does our immune system make that distinction between friend and foe? The answer lies in a small gland found in the space between our lungs, the thymus. Thymic epithelial cells (TECs) in the thymus help develop certain immune cells called T-cells, which attack enemy cells but leave our own alone. However, as researchers at UC Riverside recently realized, TECs can do even more than that.
These scientists have discovered new types of TECs that are important not only for their role in T-cell development but also for regulating other thymus functions. One such function is the regulation of thymus involution, or the gradual decrease in size and capability of the thymus as we age. As our thymus shrinks, our immune system weakens. The discovery of these new TECs therefore could help future researchers develop novel therapies to restore immune system function. The study also found that the new TECs can collect pieces of invading pathogens, passing this information to other immune cells and stimulating the immune system to remove pathogens more effectively.
These discoveries provide researchers with a greater understanding of both the thymus and the immune system as a whole, furthering the development of clinical therapies for enhanced immune system function. So the next time you’re lying in bed sick with the flu, take heart! Researchers are working hard to improve our immune systems, one cell at a time.
This study was led by graduate student Diana Del Castillo and Professor David Lo at the University of California Riverside’s Biomedical Sciences Department.
Managing Correspondent: Jenny Kim
Press Article: Study reports discovery of new cell type in thymus (UC Riverside News)
Original Journal Article: Thymic mimetic cells function beyond self-tolerance (Nature)