FIG. 4.
Long-term memory in the genital organ-associated lymphoid tissues and spleens of mice intranasally infected with Flu/P18IIIB virus. Five mice intranasally infected with 3 × 105 PFU of Flu/P18IIIB virus were vaginally infected with 2 × 107 PFU of vPE16 4 months later. Naive (unimmunized) mice were also infected with vPE16 and served as a control representing the magnitude of a primary response. ILNs (A) and spleens (B) were removed at day 3 or 5 after vaginal challenge. Following 3 days of in vitro culture without antigen stimulation for ILN and 6 days of culture with irradiated P18-I10 peptide-loaded stimulators for spleen cells, the presence of CTL effectors was evaluated in a 51Cr release assay, with P18-I10 peptide-pulsed P815 cells used as targets. The results are plotted as the mean net percentage of specific lysis (± standard deviation) at an E:T ratio of 50:1.