An Irish research team has made new and potentially controversial findings about the liver, discoveries which could open up fresh possibilities in the treatment of liver disease.
The study indicates that the liver can produce its own lymphocytes, a type of white blood cell that is involved in fighting off infection. It also appears that the liver-based lymphocytes tend to remain in the liver tissues rather than circulating throughout the body, explained Dr Cliona O'Farrelly, research director at St Vincent's Hospital education and research centre.
Dr O'Farrelly is the 1998 winner of the Irish Research Scientists' Association annual gold medal award for research. She is the first woman recipient of the award, which is given after a review and selection process involving other research scientists.
She was chosen "for the outstanding quality of her work and her personal commitment to the public understanding of science", according to Dr John Donovan, executive secretary of IRSA. The award was presented over the weekend at the association's annual G. Johnstone Stoney Summer School.
The liver work is only one element of an extensive research programme under way at St Vincent's, Dr O'Farrelly explained. The centre involves between 26 and 30 full-time researchers working in seven or eight project groups. Dr O'Farrelly is in overall charge of research but is specifically involved in the team's working on liver and gastrointestinal immunological studies.
It was one of the very few dedicated research centres attached to a teaching hospital, she said. Its particular strength lay in the fact that fundamental medical research work at the centre was matched by clinical studies and feedback from physicians working in the hospital. It was a "unique concept" she added, and it was "the team that has made everything possible".
She has been director for five years and in that time the centre had attracted five Newman Scholars, post-doctoral fellows who carry out intensive research for three years. Funding comes from UCD but also from grant agencies such as the Health Research Board.
The liver lymphocytes are a Ttype cell although their function as T-cells is not yet clear. Lymphocytes are produced from stem cells which arise in the bone marrow and then "differentiate" to form white cells. Lymphocytes are also associated with the thymus where they are modified, hence the name, T-cells. The liver was not considered an originating site for T-cells, she said, but her work suggests that the liver may in fact harbour a unique group of lymphocytes and they may either differentiate there from stem cells or arise as stem cells in the liver.
"These are very unusual populations of lymphocytes that are very different to other populations and we believe they differentiate in the liver," she said. "We have some evidence that the lymphocytes that arise in the liver stay there." They had also seen dividing stem cells in the liver, which suggested that they could originate there.
The liver immunology group is currently trying to understand these lymphocytes, why and how they are different and what their role might be. Because T-cells were associated with the immune response, understanding what these cells did could help towards better treatments, she said.
Hepatitis C was an example. Some people with the virus do not go on to develop disease while others do, for unknown reasons. The presence of the virus could trigger the T-cells to view healthy tissues as "anti-self" and so attack them, causing liver damage. Or perhaps the immune system over-responds and cannot be shut down, again leading to damage.
Liver transplantation may also benefit from the research. Patients tend to tolerate foreign liver tissues better than other organ donations, she said. It may be because host stem cells differentiate into lymphocytes in the donated liver, and so better resemble "self". The work is only beginning and it will be some time before the St Vincent's research team can determine what these lymphocytes do. It opens up a whole new area of study, however, which could yield important results.