Researchers around the world are exploring methods to collect T cells with receptors targeting cancer or other illnesses like the SARS-CoV-2 virus from patients, expand those cells in the lab and then return this larger population of targeted T cells to patients to boost their immune response. Now scientists from the Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at UCLA have developed a technique that will enable researchers to more efficiently isolate and identify rare T cells that are capable of targeting viruses, cancer and other diseases.
The approach could increase scientists’ understanding of how these critical immune cells respond to a wide range of illnesses and advance the development of T-cell therapies. This includes immunotherapies that aim to boost the function and quantity of cancer or virus-targeting T cells and therapies intended to regulate the activity of T cells that are overactive in autoimmune diseases such as diabetes and multiple sclerosis.
“This addresses challenges at the heart of finding T-cell receptors for treating cancer and other diseases, as well as viral infections — from acute viruses like the virus that causes COVID-19 to chronic viruses like Epstein Barr or herpes,” says Owen Witte, MD, founding director of the UCLA Broad Stem Cell Research Center.
The study describes how the new method, called CLInt-Seq, combines and improves upon existing techniques to collect and genetically sequence rare T cells. “T cells are critical for protecting the body against both infections and cancers,” says Pavlo Nesterenko, a graduate student in Dr. Witte’s lab. “They’re both the effectors and organizers of the body’s adaptive immune response, which means they can be used as therapeutics. Studying their dynamics can shed light on overall immune activity.”
T cells stand out from other immune cells, because they are equipped with molecules on their surfaces called T-cell receptors. Every T-cell receptor is capable of recognizing one specific antigen. For example, one T-cell receptor might recognize an antigen from the virus that causes the common cold, while another might recognize an antigen from breast cancer.
When researchers attempt to isolate T cells with specific receptors using traditional methods, they end up capturing bystander cells. CLInt-Seq alleviates this problem by incorporating a technique that enables researchers to distinguish T cells with receptors of interest from most bystander cells. Additionally, the process of isolating T cells with specific receptors, known as cross-linking, degrades the T cells’ RNA and makes mRNA sequencing for analysis very challenging. CLInt-Seq overcomes this hurdle by utilizing a method of cross-linking that is reversible and thus preserves the T cells’ RNA.
Moving forward, Dr. Witte is utilizing this technology to address a number of scientific questions, including identifying T-cell receptors that react to the SARS-CoV-2 virus and developing T-cell therapies for prostate cancer.
— Tiare Dunlap
“Droplet-based mRNA Sequencing of Fixed and Permeabilized Cells by CLInt-seq Allows for Antigen-specific TCR Cloning,” PNAS, January 19, 2021