FIG. 3.
Epitope specificity of the polyclonal response following in vitro stimulation of PBMC cryopreserved in the year 2001 with influenza A viruses (H3N2) containing different variants of the epitope. PBMC of HLA-B35+ donors, aged between 30 and 50 years, were stimulated in vitro with A/Victoria/3/75 (A, C, and E), containing the NP418-426/1972 variant, or Resvir-9 (B, D, and F), containing the NP418-426/1980 epitope, as described previously (3). After 8 days, the effector cells were tested for lytic activity against target cells incubated with the peptides corresponding to NP418-426/1980 (▿), NP418-426/1972 (□), and NP418-426/1957 (⧫). Untreated target cells (•) were included in each assay as a negative control. Mean percentages of specific lyses of two independently repeated experiments are shown for donors 5972 (A and B), 5017 (C and D), and 5991 (E and F).