Organ transplantation

Dr. Claude Daniel and his research teamZoomZoom
© Armand-Frappier Museum

Article published in the Courrier Laval April 23, 2006.

This year, National Organ Donation Week will be held from April 24 to April 30. Everywhere in the country, citizens will be sensitized to the importance of signing their health insurance cards to authorize harvesting of their organs and tissues when they die. At the same time, the work of researchers who are attempting to eliminate organ rejection and to improve the quality of life of organ recipients will be showcased.

This is the case of Dr. Claude Daniel, professor-researcher at the INRS-Institut Armand-Frappier. Dr. Daniel is responsible for three Quebec laboratories in charge of establishing compatibility between donors and patients waiting for an organ transplant. Dr. Daniel also studies the mechanisms of organ rejection.

Some of these mechanisms are already known and a few medications, known as immunosuppressors, are used to suppress the immune response in patients who have received an organ. The most well known of these medications is called Cyclosporin. In the short term, these medications are very effective and depending on which organ is transplanted, survival rates of 80 to 95% can be expected one year after the transplantation. However, these medications decrease the immune system’s ability to defend itself against the development of cancer and against microbial infections as benign as the common cold. Furthermore, these medications have little effect on the chronic rejection that occurs a few years after the surgery. We need to build long-term tolerance of the graft while maintaining a fully competent immune system.

To this end, Dr. Daniel is interested in the regulation of the response that leads to the rejection of the transplanted organ. When a patient has just received an organ, the cells of the recipient’s immune system recognize the donor cells; this reaction is called direct alloreactivity. This very vigorous response is attenuated by commercial immunosuppressors. In parallel, an indirect response occurs, whereby some foreign molecules present on the newly received organ are degraded and presented by the cells of the recipient’s immune system. This response is constant in time and is at the origin of organ rejection.

Dr. Daniel has developed a unique study model to identify physiologic mechanisms specific to direct and indirect alloreactivity. He is specifically interested in defining the interaction between the cells of the immune system involved in the rejection, as well as where these interactions occur. This information should make it possible to develop better targeted therapeutic strategies and to decrease the incidence of chronic organ transplant rejection.

This article was written with the collaboration of Dr. Claude Daniel, professor-researcher at the INRS-Institut Armand-Frappier, whose research is partially supported by the Canadian Institutes of Health Research and the Fondation Roche pour la recherche en transplantation d'organes.