In a discovery that might be likened to finding medicines version of the Loch Ness monster, a research team from Johns Hopkins Medicine, IBM Research and four collaborating institutions is the first to document the existence of long-doubted "X cell," a "rogue hybrid" immune system cell that may play a key role in the development of type 1 diabetes.
The researchers report the unusual lymphocyte (a type of white blood cell) formally known as a dual expressor, or DE, cell in a new paper published in the journal Cell.
"The cell we have identified is a hybrid between the two primary workhorses of the adaptive immune system, B lymphocytes and T lymphocytes," says Abdel-Rahim A. Hamad, M.V.Sc., Ph.D., associate professor of pathology at the Johns Hopkins University School of Medicine and one of the authors of the paper. "Our findings not only show that the X cell exists, but that there is strong evidence for it being a major driver of the autoimmune response believed to cause type 1 diabetes."
Type 1 diabetes, formerly known as juvenile diabetes or insulin-dependent diabetes, is a chronic condition in which there is destruction of the beta cells in the pancreas that produce insulin, the hormone that regulates a persons blood sugar level. Diagnosed mostly in childhood but present at all ages, the disease accounts for between 5% and 10 % of all diabetes cases in the United States or about 1.3 million people. Although most experts believe it to be an autoimmune disorder where the immune system mistakes normal, healthy beta cells as hazards and eliminates them the underlying mechanism at the cellular level has been difficult to define.
Hamad and his colleagues believe that they may be the first to do so. However, they caution that more analysis is required to directly link the X cell to the development of type 1 diabetes.
"What is unique about the entity we found is that it can act as both a B cell and a T cell," Hamad says. "This probably accentuates the autoimmune response because one lymphocyte is simultaneously performing the functions that normally require the concerted actions of two."
B and T lymphocytes each possess distinctly different cell receptors the B cell receptor, or BCR, and T cell receptor, or TCR, respectively that work together to help identify and target antigens; the bacteria, viruses and other foreign invaders that trigger an immune response. Normally, this defense begins when the trespasser is engulfed by a white blood cell called an antigen presenting cell, or APC. The name arises from the fact that an antigenic protein from the ingested intruder is "presented" on the surface of the APC.
Sean
Phone: 
E-mail: 
Address: