Immune system's quality control mechanism 'discovered'

An international team, led by Monash University, has solved a 15-year puzzle by working out the structure and function of a protein called pre-T alpha that is essential in guiding the correct expression of various receptors expressed by T lymphocytes, white blood cells of the immune system.

These receptors, known as T cell receptors, recognise unique components of microbial pathogens.

Team leader Prof Jamie Rossjohn said understanding the structure of pre-T alpha explains a fundamental step in T cell development and anti-microbial immunity.

"We showed that the pre-T alpha molecule not only assists in the expression of functional T cell receptors but it also allows two molecules to bind together, which alerts the T cell that this receptor is constructed properly, allowing the T cell to move to the next step in its development," he said.

According to team member Prof Jim McCluskey from the University of Melbourne, without T cell receptors we would be profoundly immunodeficient and therefore pre-T alpha plays an essential role in ensuring proper immunity.

"Additionally, there is some evidence that pre-T alpha may also be involved in some childhood leukaemias, so this new knowledge of how it functions may be important in diagnosis and treatment of acute lymphoblastic leukaemia," he said.

The findings have been published in the latest edition of the 'Nature' journal.