A team of Canadian and Finnish scientists has identified a protein able to stimulate the production of T-cells, the white blood cells involved in the recognition and the elimination of infectious agents. The discovery by researchers of the Institute for Research in Immunology and Cancer (IRIC) at the Université de Montréal in Canada and the University of Oulu in Finland could help to combat age-related declines in immune response.

Thanks to the work of Dr. Claude Perreault and his team, which identified the properties of a protein called Wnt4, it is now possible to envision news ways to reverse the age-related decline of the immune system. "Thymic atrophy is a major public health problem," said Dr. Perreault.

"It compromises the efficacy of vaccination and weakens the resistance to common viruses, for instance to the respiratory syncytial virus (RSV), which is responsible each year for the hospitalization of more than 150,000 people in the U.S. This is due to the fact that 'old' T cells are not equipped to face the threat of new foreign bodies, whether they are viruses or tumours."

The atrophy of the thymus, a small gland at the base of the neck where T cells mature, is one of the most obvious signs of the age-related decline of the immune system. This decline becomes significant towards the age of 50. It is caused not only by a decreased output of T cells from the thymus, but also by a decreased ability to recognize new antigens. The result is an increased susceptibility to infection as well as a lowered resistance to the immunosuppressive effects of chemotherapy.

By inducing an overproduction of the Wnt4 protein in the cells of the mouse immune system, Dr. Perreault and his collaborators were able to observe the stimulatory effect this protein exerts on the development of white blood cells. Using molecular markers that are specific to the different stages of cell maturation, IRIC researchers determined that elevated levels of Wnt4 led to a marked increase in the number of white blood cell progenitors, and of immature T cells in the thymus in particular.

Release date: July 22, 2008
Source: University of Montreal