Fig. 3.

The ability of nonstimulatory MHC–peptide ligands to enhance antigen recognition depends on their quantity rather than their sequence. A small amount of antigen was added to RMA-S cells (OVA). This resulted in very low expression of the epitope for the anti-OVA–K^b. Other nonstimulatory peptides were titrated in to increase the overall amount of K^b expression. This increased expression of K^b correlated with increased activation of thymocytes. Used with permission from Yachi et al. (2007)