Researchers at University Medical Center Utrecht have uncovered a previously underappreciated mechanism that helps immune cells to respond rapidly to infections. Using advanced long-read RNA sequencing, the team shows that alternative RNA splicing, which means how genes are edited into different messenger RNA variants, plays a central role in shaping immune responses. The findings provide new insights into immune-mediated diseases (such as infections, rheumatoid arthritis and lupus) and may open the door to more targeted therapies.

The study, published in Nature Communications, focused on monocytes, a type of innate immune cell that acts as a first responder to pathogens. When these cells encounter bacterial components such as cell wall components, they must quickly adapt to mount an effective defense. While earlier research has largely examined changes in overall gene expression, this study zoomed in on RNA isoforms, the different transcript variants that a single gene can produce.

Using long-read RNA sequencing, researchers at the Center for Translational Immunology (University Medical Center Utrecht, the Netherlands) generated a comprehensive map of full-length RNA transcripts in human monocytes before and after activation. They identified more than 24,000 isoforms, of which the majority have never been described, revealing a previously hidden layer of molecular complexity.