Today’s New York Times reports that two groups of scientists have independently made major discoveries about the immune system. One group is led by Allan Bradley and Martin Turner in England and the other by Klaus Rajewsky at Harvard Medical School.

“These findings demonstrate the importance of this level of control in the immune system and will lead immunologists to rethink how the immune system works,” said Dr Martin Turner, Head of the Laboratory of Lymphocyte Signalling and Development at the Babraham Institute.

According to today’s issue of the journal Science, Friday Apriil 27, the discoveries number not just 2 but 4:

In a flurry of papers, three of which appear on pages 575, 604, and 608 of this issue of Science, four independent groups have for the first time deleted mouse genes for microRNAs, RNA molecules that can modulate gene behavior, with profound effects.

The Times writer says:

Dr. Bradley’s in Cambridge, England found that the genetically engineered mice did not respond well to vaccination and failed to develop immunity. Without miR-155, they were unable to generate important cytokines, the cell-to-cell signaling proteins that coordinate the various components of the immune system.

Dr. Rajewsky’s team found that without miR-155, the immune system was no longer able to select antibody-making cells of the right specificity to attack invaders.

See Studies Reveal an Immune System Regulator

The UK team’s press release explains:

A role for a microRNA in the immune system has been shown by study of one of the world’s first microRNA knockout mouse, reported Friday 27 April in Science. The microRNA acts as a lynchpin to balance the response of immune defences and the researchers suggest the corresponding human gene will have a similar vital role.

Cells of the immune system in the knockout mice do not work as well as normal cells and the mice develop symptoms similar to those of human autoimmune disease. They are also less able to resist infection by bacteria, such as Salmonella. The team suggest that the equivalent human microRNA will play a major role in the human immune system.

“Very little is known about the function of the hundreds of microRNA genes,” said Dr Antony Rodriguez, lead author on the paper from the UK’s Wellcome Trust Sanger Institute. “Although plentiful, this class of genes had never before been knocked out in mice, the best model organism for human disease.”

The effects of the miR-155 knockout swept across the immune system. The team showed that, although knockout of miR-155 did not appear to affect normal growth and development of cells in the immune system, each major cell type – T-cells, B-cells and dendritic cells – performed less well.

“These findings demonstrate the importance of this level of control in the immune system and will lead immunologists to rethink how the immune system works,” said Dr Martin Turner, Head of the Laboratory of Lymphocyte Signalling and Development at the Babraham Institute.

“”This dramatic finding reflects a large amount of work by collaborating groups,” said Professor Allan Bradley, Director of the Wellcome Trust Sanger Institute. “Showing that knocking out a microRNA has such dramatic effects opens new doors to understanding this novel class of gene regulation, with consequences for human health and disease.”

SOURCE — full story, Welcome Trust Sanger Institute