Priming of cytotoxic T lymphocytes at various stages of ontogeny with transfectoma cells expressing a chimeric Ig heavy chain gene bearing an influenza virus nucleoprotein peptide.

The amino acid residues 147-161 of the nucleoprotein (NP) of influenza virus represent a T cell epitope recognized by cytotoxic T cells (CTLs) in association with Kd class I molecules. When SP2/0 myeloma B cells are transfected with a chimeric heavy chain gene bearing this particular NP(147-161) peptide, they are lysed by CTLs specific for the NP(147-161) peptide. Cells that are transfected with this heavy chain chimera and the parental light chain secreted a soluble Ig-NP chimera and were also lysed by the CTLs. Herein, we present evidence that transfectoma cells are able to induce in vitro proliferation of NP specific CTL, whereas immobilized Ig-NP chimeras do not. Furthermore, the transfectoma cells expressing the chimeric heavy chain prime NP specific CTLs in adult as well as in newborn mice, while SP2/0 cells coated with NP(147-161) synthetic peptide do not. These data indicate that the NP peptide needs to be cleaved from the Ig context in order to be presented to T cells and that only endogenously generated NP peptide is immunogenic.