The first lines of defense in our immune systems are specialized mobile units that check the identity of cells to determine whether they are 'self' or 'foreign.'
A team of scientists, led by Prof. Israel Pecht of the Weizmann Institute's Immunology Department, has now revealed in fine detail how the body's 'reconnaissance unit' continuously screens and inspects identity. These new findings may lead to deeper insights into the workings of the immune system, its function in health and malfunction in disease, as well as yielding new directions in pharmaceutical and medical research.
White blood cells called T cells employ specialized receptors called TCRs (T cell receptors) for cell identification. TCRs bind to molecules present on all our body's cells that act as 'self-I.D. cards.' Small fragments of bodily components bound to grooves in these molecules provide additional confirmation that the cell is ours and intruder-free. T cell receptors, when they examine the these complexes (antigens), are able to spot foreign bits, even when one amino acid in the antigen is out of order, and can pick just one infected cell out of thousands of healthy ones, even when they harbor a previously unknown virus.
How does this interaction take place" Pecht, together with colleagues in Germany and France, has now provided the first step-by-step understanding of the process. Using a method that resolves these biological events at millisecond (a thousandth of a second) intervals, they were able to show how TCR binding progresses through time. Their findings recently appeared in the Proceedings of the National Academy of Sciences (PNAS), USA.