MONTREAL, Jan. 22 (UPI) -- Canadian researchers have discovered specialized T-cells lose their effectiveness over time in some people, leading to the onset of type 1 diabetes.

T-cells suppress and regulate the body's immune responses, but in diabetes mellitus, or type 1 diabetes, the body's own immune system attacks and destroys insulin-producing islet cells in the pancreas. Patients must thereafter inject insulin daily.

"The genetic and cellular mechanisms by which the immune system goes out of control and destroys the islets has been an enigma and an area of great interest over the last few decades," said Dr. Ciriaco Piccirillo of McGill University, one of the study's authors. "For the last several years, it's been postulated that non-functional regulatory T-cells are the critical mechanism, and this study proves it."

The research was conducted on mice that were genetically engineered to model human diabetes. Piccirillo and colleagues discovered the functional potency of T-cells in the mice declined with age, leaving autoimmune responses in the pancreas unchecked. Piccirillo said that finding could lead to the development of immune system-based therapies for a range of diseases.

The study appears in the journal Diabetes.

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