SYDNEY researchers have discovered a way to alter the immune system long enough to prevent the rejection of donor tissue in a breakthrough that may remove the need for lifelong, immunosuppressant drugs in organ transplant patients.
Immunologists at the Garvan Institute of Medical Research say they temporarily adjusted the immune system of mice by injecting a mix of molecules and antibodies before transplanting a graft of islet cells, the insulin-producing cells of the pancreas.
Kylie Webster said that after two weeks 80 per cent of the mice had accepted the transplant, and continued to act as if the cells were their own without needing immunosuppressive medication for up to 10 months.
"This acceptance rate is very high for transplantation, with mice normally rejecting grafts within two to three weeks," Dr Webster said.
Chris Thomas, the chief executive of Transplant Australia, which represents 4000 transplant recipients, said removing the need for immunosuppressants would be "a major breakthrough".
Normally the immune system will recognise the transplanted organ or tissue as foreign material and attempt to destroy it with killer T cells that also fight bacteria and viruses.
To prevent rejection, transplant recipients have to take strong immunosuppressant drugs such as cyclosporin for life, leaving them less able to resist infections and greatly increasing the risk of cancer, kidney damage and high blood pressure.
Professor Jonathan Sprent and his colleagues at the Garvan, the Scripps Research Institute in California and the University Hospital of Lausanne in Switzerland developed a "complex" that boosted the number of white blood cells called T regulatory cells, which control the activity of killer T cells.
"The other side of the coin is that a superabundance of T regulatory cells prevents killer T cells from functioning, and you wouldn't want to be without killer T cells for long because they fight infections and cancers," professor Sprent said.
The study, published in The Journal Of Experimental Medicine, found injecting the complex into mice for three consecutive days induced a 10-fold increase in the number of T regulatory cells for up to two weeks.
But the researchers have yet to try other grafts such as kidneys and heart transplants. Professor Sprent also warned the results may not translate from mice to humans.
This article was originally published in Sydney Morning Herald.
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