How to Rescue the Immune System
In a study published in Nature Medicine, Loyola researchers report on a promising new technique that potentially could turn immune system killer T cells into more effective weapons against infections and possibly cancer.
The technique involves delivering DNA into the immune system's instructor cells. The DNA directs these cells to overproduce a specific protein that jumpstarts important killer T cells. These killer cells are typically repressed in patients who have HIV or cancer, said José A. Guevara-Patino, MD, PhD, senior author of the study. Guevara is an Associate Professor in the Oncology Institute of Loyola University Chicago Stritch School of Medicine.
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Guevara and colleagues reported their technique proved effective in jumpstarting defective immune systems in immuno-compromised mice and in human killer T cells taken from people with HIV.
Guevara said a clinical trial in cancer patients could begin in about three years.
The study involved killer cells, known as CD8 T cells, and their instructor cells, known as antigen-presenting cells. The instructor cells instruct CD8 T cells to become killer T cells to kill infected cells or cancer cells -- and to remain vigilant if they reencounter pathogens or if the cancer comes back.
In addition to getting instructions from the antigen-presenting cells, CD8 T cells need assistance from helper T cells to become effective killers. Without this assistance, the killer T cells can't do their job.
In patients who have HIV, the virus destroys helper T cells. In cancer patients, helper T cells also are affected. Among a tumor's insidious properties is its ability to prevent killer T cells from attacking tumors. It does this by putting helper T cells into a suppressed stage, limiting their ability to assist CD8 T cells, said Andrew Zloza, MD, PhD, one of the leading authors of the study.
In the study, snippets of DNA were delivered into skin instructor cells by a device known as a gene gun. The DNA directed the instructor cells to produce specific proteins, which act like molecular keys. When CD8 T cells interact with the instructor cells, the keys unlock the CD8 T cells' killer properties -- jumpstarting them to go out and kill pathogens and cancer cells.
With the use of this technique, the killer T cells would not need the assistance of helper T cells. So even if a tumor were to put the helper T cells in a suppressive cage, the killer T cells would still be able to go out and kill cancer cells. Researchers expect that future studies using the technique will make it applicable to many diseases, including cancer.
Source: Loyola University Health System
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