Dana-Farber Cancer Institute scientists to identify cells (CF8+ T regulatory cells) in mice that prevent the immune system from attacking the animals’ own cells, protecting them from autoimmune diseases such as multiple sclerosis, type 1 diabetes, and lupus. The significance of this work is that CD8+ Treg cells represent a new lever for raising or lowering the strength of the immune response.
CD8+ Treg cells mingle with cells known as follicular T-helper cells, which are intermediaries that prompt the immune system’s B cells to make disease-fighting antibodies. The meeting with CD8+ Treg cells essentially shuts off the follicular T-helper cells, preventing them from interacting with B cells. No interaction means no production of antibodies, which means no assault on an animal’s normal, healthy cells.
The critical point of contact between CD8+ Treg cells and follicular T-helper cells is a protein on the helper cells called Qa-1. When Kim and her colleagues bred a strain of mouse with abnormal Qa-1, the animals developed a form of lupus. The reason: the CD8+ Treg cells couldn’t latch onto the defective protein, leaving the follicular cells free to order the B cells to produce antibodies, some of which targeted the animals’ own tissue.