FIG. 2.

Persistent antigen is present in the spleen and lymph nodes. CFSE-labeled OT-I cells were transferred into mice 22 or 28 days postinfection, and lymphocytes were harvested 22 to 24 h later and placed in culture for 3 days in IL-2-supplemented medium. Histograms show the degree of CFSE dilution by CD8⁺ CD45.1⁺ cells harvested from the inguinal or cervical LN or spleens of previously infected mice. The SIINFEKL peptide (1 μg/ml) was added to spleen cultures as a positive control.