UCLA scientists develop method to more efficiently isolate and identify rare T cells

January 11, 2021

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.

The study, published today in Proceedings of the National Academy of Sciences, 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," said Pavlo Nesterenko, first author of the new paper and a graduate student in the lab of Dr. Owen Witte. "They're both the effectors and organizers of the body's adaptive immune response, which means they can be used as therapeutics and 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 that recognize fragments of foreign proteins called antigens.

Our bodies produce millions and millions of T cells per day and each of these cells has its own distinct set of receptors. Every T-cell receptor is capable of recognizing one specific antigen. 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, for example.

When a T cell encounters an antigen its receptor recognizes, it springs to action, producing large numbers of copies of itself and instructing other parts of the immune system to attack cells bearing that antigen.

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.

"The problem is that in most populations of cells we have access to, whether it be from peripheral blood or samples taken from other parts of the human body, T cells with receptors of interest are found in very low numbers," said Witte, senior author of the paper and founding director of the UCLA Broad Stem Cell Research Center. "Existing methods for capturing and identifying these T cells are labor-intensive and need improvement."

Part of the reason this process is inefficient is that when T cells recognize the antigen for which they have the corresponding receptor, they send out signals that prompt other cells nearby to partially activate.

"These so-called bystander cells are excited by the activity around them, but are not really capable of reacting to the antigen that provoked the immune response," said Witte, who holds the presidential chair in developmental immunology in the department of microbiology, immunology and molecular genetics and is a member of the UCLA Jonsson Comprehensive Cancer Center.

When researchers attempt to isolate T cells with specific receptors using traditional methods, they end up capturing many of these 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.

Isolating T cells with specific receptors is only the first step. In order for these isolated cells to be useful, they need to be analyzed using droplet-based mRNA sequencing, also known as Drop-seq, which can measure messenger RNA expression in thousands of individual cells at once.

"Once you know the sequence of a T-cell receptor of interest, you can use that information to develop therapies that either make more of that cell in the case of fighting cancer and viruses or introduce regulatory T cells with this receptor sequence to curb an overactive immune response in a given area," Nesterenko said.

The process of isolating T cells with specific receptors requires that the cells' contents are fixed in place using chemicals that form bonds between the proteins inside each cell and their surroundings - this technique is known as cross-linking. Unfortunately, cross-linking degrades the T cells' RNA, which makes Drop-seq 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.

"The innovation of this system is that it combines an improved method that identifies T-cell receptors with more specificity with a chemical adaptation that makes this process compatible with droplet-based mRNA sequencing," Witte said. "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."

Moving forward, the Witte lab 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.
-end-
This research was funded by the National Cancer Institute, the Parker Institute for Cancer Immunotherapy, a UCLA Tumor Immunology Training Grant and the UCLA Broad Stem Cell Research Center, including support from the Hal Gaba Director's Fund for Cancer Stem Cell Rese

University of California - Los Angeles Health Sciences

Related Cancer Articles from Brightsurf:

New blood cancer treatment works by selectively interfering with cancer cell signalling
University of Alberta scientists have identified the mechanism of action behind a new type of precision cancer drug for blood cancers that is set for human trials, according to research published in Nature Communications.

UCI researchers uncover cancer cell vulnerabilities; may lead to better cancer therapies
A new University of California, Irvine-led study reveals a protein responsible for genetic changes resulting in a variety of cancers, may also be the key to more effective, targeted cancer therapy.

Breast cancer treatment costs highest among young women with metastic cancer
In a fight for their lives, young women, age 18-44, spend double the amount of older women to survive metastatic breast cancer, according to a large statewide study by the University of North Carolina at Chapel Hill.

Cancer mortality continues steady decline, driven by progress against lung cancer
The cancer death rate declined by 29% from 1991 to 2017, including a 2.2% drop from 2016 to 2017, the largest single-year drop in cancer mortality ever reported.

Stress in cervical cancer patients associated with higher risk of cancer-specific mortality
Psychological stress was associated with a higher risk of cancer-specific mortality in women diagnosed with cervical cancer.

Cancer-sniffing dogs 97% accurate in identifying lung cancer, according to study in JAOA
The next step will be to further fractionate the samples based on chemical and physical properties, presenting them back to the dogs until the specific biomarkers for each cancer are identified.

Moffitt Cancer Center researchers identify one way T cell function may fail in cancer
Moffitt Cancer Center researchers have discovered a mechanism by which one type of immune cell, CD8+ T cells, can become dysfunctional, impeding its ability to seek and kill cancer cells.

More cancer survivors, fewer cancer specialists point to challenge in meeting care needs
An aging population, a growing number of cancer survivors, and a projected shortage of cancer care providers will result in a challenge in delivering the care for cancer survivors in the United States if systemic changes are not made.

New cancer vaccine platform a potential tool for efficacious targeted cancer therapy
Researchers at the University of Helsinki have discovered a solution in the form of a cancer vaccine platform for improving the efficacy of oncolytic viruses used in cancer treatment.

American Cancer Society outlines blueprint for cancer control in the 21st century
The American Cancer Society is outlining its vision for cancer control in the decades ahead in a series of articles that forms the basis of a national cancer control plan.

Read More: Cancer News and Cancer Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.