Using a new imaging technique, researchers from the University of Texas at Austin for the first time captured the process in which developing killer T-cells (purple and white) are tested by dendritic cells (yellow), and others, to see if they react to normal proteins from the body, called self-antigens. If a T-cell touches one of these cells and its receptors happen to match the self-antigen displayed, calcium levels spike within the T-cell (turning it whiter), indicating that it has failed the safety check. Left to roam the body, an autoreactive T-cell would attack the body’s own cells. Fortunately, in most cases, this calcium signal triggers the T-cell to self destruct.

The research was conducted by Lauren Ehrlich and Jessica Lancaster. Video credit: University of Texas at Austin.