FIG. 2.

H3N2 influenza viruses isolated between 1969 and 1996 sensitize target cells for NK lysis more efficiently than recent virus isolates (1999 to 2000). Representative results from ⁵¹Cr release assays comparing the percentage of specific lysis of uninfected 143BTK⁻ cells (dashed line) to that of cells infected with different influenza virus isolates by unseparated PBMC effectors (A) or isolated CD56⁺ CD3⁻ NK cells (B) at a range of E:T ratios. Solid lines and filled symbols are used to denote target cells infected with older virus isolates (1969 to 1996), and dotted lines and open symbols denote target cells infected with more recent viruses.