Viral recognition by influenza A virus cross-reactive cytotoxic T (Tc) cells: the proportion of Tc cells that recognize nucleoprotein varies between individual mice.

L cells (H-2k) transfected with DNA coding for the A/NT/60/68 influenza nucleoprotein (NP) gene have been found previously to provide a target cell for cytotoxic T (Tc) cells. In this report we have studied the repertoire of cytotoxic memory cells in mice of different strains primed by infection with several influenza A subtypes. L cells transfected with NP and Db genes enabled us to estimate the proportion of A virus cross-reactive Tc cells specific for NP. The most striking feature of our results was variation in the frequency of NP-specific Tc cells between individuals of an inbred mouse strain. Occasional individuals, although showing a strong A virus cross-reactive Tc response, had no A virus cross-reactive Tc cells that recognized NP. The NP-directed Tc repertoire represented between 0-40% of lysis of target cells infected with a heterologous type A virus. Thus, a significant proportion of A virus cross-reactive Tc cells must have different specificities for type A influenza virus. In C3H-H-2o2 mice, Dk is a low responder allele for NP recognition by Tc cells.