Interestingly, there were no differences in function or phenotype characteristics for the D b NP 366 + CD8 + and NPN3A + CD8 + T cells, although those two CTL sets had a high proportion of different TCR clones. This is in accordance with previous studies showing that the simultaneous production of antiviral cytokines [29] and IL-7R [20] expression is antigen dose-rather than magnitude-related. Conversely, levels of the CD62L [38, 39, 40] activation marker differed for the D b NP 366 + CD8 + and NPN3A + CD8 + populations, indicating that response magnitude has some relationship to the activation status of CD8 + T cells [40, 41, 42] which may, perhaps, reflect the extent of CTL proliferation.