Characteristics of secondary cytotoxic T-cell responses in mice infected with influenza A viruses.

The cytotoxic T-cell response in mice infected with type A influenza viruses is dominated by a highly cross-reactive component. Previous experiments showed that after primary immunization the cytotoxic T-cell response apparently consists of a small but significant portion which is specific for the immunizing virus, and a larger component which is highly cross-reactive among all A strain viruses. The present study concentrates on the specificity of the T-cell response after secondary stimulation, using various combinations of type A virus strains. The underlying rationale was to determine whether there was any discernable pattern in the T-cell response which parallels the serologically defined antigenic pattern of influenza.That a virus strain-specific set of precursors does exist was evident in the primary response and even more so upon secondary challenge with the homologous virus (using an adoptive transfer protocol). However, upon secondary challenge with a heterologous influenza virus, this specific component was not evident no matter how closely related serologically the two challenge viruses were. No obvious relationships could be found between serologically defined antigenic patterns and the capacity to stimulate a secondary T-cell response specific for a particular type A influenza virus.