The Nobel week kicked off with the medicine/physiology prize going jointly to three scientists. Mary Brunkow, Fred Ramsdell and Shimon Sakaguchi have been honoured for their work on deciphering the intricacies of the immune system, in particular, the mechanism that prevents it from attacking the body’s own cells while fighting foreign pathogens trying to enter the body. Most of this work had been done in the 1980s and 1990s, and the discoveries are already having an impact on the treatment of auto-immune diseases, cancer and organ transplants.
The immune system protects the body against diseases by neutralising disease-causing pathogens like bacteria and viruses. Key to this process is the ability of the immune system — in particular, a special kind of white blood cells, called T-cells — to distinguish between the cells of the pathogen and the host body. When this does not happen properly, it leads to auto-immune diseases, in which the T-cells start damaging the body’s own cells. Why this does not happen in a healthy body is what the Nobel Prize winners were able to figure out. T-cells are trained to be selective in their approach but this training is not perfect. Sakaguchi identified a special group of T-cells, called regulatory T-cells, or Tregs, that suppresses the activity of other T-cells if they had a propensity to attack the body’s own tissues. Brunkow and Ramsdell later discovered the gene that enables some T-cells to function as Tregs. Together, they complete the picture of the immune system.
Their discovery has important implications in the treatment of auto-immune diseases. Organ transplants get complicated because the immune system identifies them as foreign, and begins to attack them. Scientists hope that regulation of Tregs activity could smoothen this process. In cancer, sometimes the reverse process happens. The cancerous cells attract too many Tregs, so that the normal T-cells, which should ideally have been killing the cancerous cells, become ineffective.
