A new procedure that prevents faulty immune responses in mice may eventually help treat patients with rheumatoid arthritis, according to research published in the Journal of Clinical Investigation.

Researchers at Harvard Medical School used a medical procedure to stimulate the CD8 regulatory T cells in arthritic mice. When activated, the CD8 cells keep the immune system from attacking joints and causing inflammation — a common cause of rheumatoid arthritis. If enough of the cells are activated, RA symptoms abate and, in some cases, disappear completely.

“These are regulatory cells, and they inhibit the response that can destroy the body’s own tissues, including in the joints,” says Harvey Cantor an immunologist at Harvard Medical School and an author of the study.

“This strategy seems to be remarkably effective in the animal model that we’ve studied,” he adds.

Affecting an estimated 1.5 million Americans, rheumatoid arthritis (RA) is an often painful swelling and inflammation of the joints, thought to be the result of an overactive immune system. Previous research has focused on the chemicals that cause joint destruction, but Cantor’s approach targets regulatory cells that help prevent an excessive immune response.

“If you impair these [CD8 regulatory T] cells, animals develop autoimmune disease,” Cantor says. “So we figured if we use these cells maybe we can inhibit the disease.”

Researchers followed five mice over the course of almost three months, applying the CD8 treatment three times. The results were encouraging.

“This method was efficient for the prevention and treatment of rheumatoid arthritis in mice,” says Hye-Jung Kim, an immunologist at Harvard Medical School and co-author of the study.

However, Kim stresses that while the study was successful, the procedure is still far from being included in clinical trials. The team needs to test the same system on human cells before continuing on to human tests.

“We are looking at a better animal model with human cells…where we use human cells and ask the same question. We can use that as a basis for human trials,” Cantor says.

“These are very encouraging results, but they’re in animals and we have to see if it translates into people.”