"What we discovered in the peripheral blood of the MS patients were T cells that appeared to be primed for action against EBV," said Nancy Edwards, a research scholar at Howard Hughes Medical Institute.
“Epstein-Barr virus does not cause MS, but the immune response to this virus is different in MS patients. Very recent investigations have shown that such enhanced responses occur years before onset of clinical symptoms of MS,” said first author Jan Lünemann, a neurologist and immunologist at The Rockefeller University in New York.
Lünemann, Edwards, and colleagues began by collecting T cells from 20 untreated patients with MS and 20 volunteers who had been infected by Epstein-Barr virus but did not have the autoimmune disease. They then isolated from each patient the T cells that specifically responded to one viral protein, called Epstein-Barr virus-encoded nuclear antigen1 (EBNA1). A series of experiments revealed a pattern among the EBNA1 T cells in MS patients that was not seen in the healthy volunteers. “We saw a dual effect - not only was there an increased number of EBNA1 responsive T cells, but these T cells proliferated to a greater extent when they were stimulated by antigens,” said Edwards.
"We also examined T-cell responses to influenza hemagglutinin, antigens derived from cytomegalovirus, and even EBV antigens other than EBNA1," Edwards said. "The T-cell responses to these were all normal in MS patients, indicating a distinct role for EBNA1 in the disorder." As expected, the T cells in the healthy volunteers activated only in the presence of a specific group of peptides. But, Edwards said, “EBNA1-specific T cells from the MS patients not only increased in frequency, but also recognized a much broader region of the protein, compared to healthy people who carried the EBV virus."
The findings could lead to new therapeutic strategies for better control of the damage caused in this autoimmune disorder.
MEDICA.de; Source: Howard Hughes Medical Institute