High sensitivity, low affinity--paradox of T-cell receptor recognition.

The recent findings demonstrating the unexpected low affinity of a T-cell receptor towards its ligand have created a puzzle, as the high sensitivity and exquisite specificity of T cells and the low affinity of T-cell receptors are, at first glance, not compatible features. However, the close scrutiny of the parameters of T-cell antigen recognition in the actual space where ligation events occur has revealed that the low affinity of the T-cell receptor is perfectly compatible with T-cell function.