T cell receptors are expressed either individually (red arrows) or as multivalent groups (black arrows). Only grouped TCRs respond to low-dose antigen.
T cell receptors (TCRs) band together to detect minute amounts of antigen, according to Schamel and colleagues on
page 493. Their new work shows that TCRs are expressed on the surface of resting T cells either individually or in groups. The grouped TCRs, but not the solitary receptors, were triggered by low dose antigen, suggesting that these receptors must cooperate when antigen is scarce.Whether TCRs exist as solitary entities or whether they group together is a long-standing matter of debate. Previous studies have failed to uncover evidence of grouped (multivalent) TCRs, but this may have resulted from dismantling of the groups as a result of overly harsh purification techniques.
In the new study, Schamel et al. gently coaxed the TCRs from the...
