CD4+ and CD8+ mediated cellular immune response to recombinant influenza nucleoprotein.

Abstract The stimulatory properties of soluble recombinant influenza nucleoprotein (NP) on purified CD4 + and CD8 + T cells from young and elderly individuals were studied. Recombinant influenza NP failed to induce proliferation of resting CD4 + and CD8 + T cells in the absence of IL-2. Addition of small amounts of IL-2, however, led to strong proliferation of resting CD4 + and CD8 + T cells from young and elderly donors. NP-reactive CD4 + and CD8 + T cell lines from both age groups grew equally well under long-term culture conditions. T cell lines raised to live influenza virus could recognize recombinant influenza NP and showed a substantial proliferative response. Stimulation of CD8 + T cells is presumably due to cross-presentation, as EBV-transformed MHC class I-positive cell lines, which are incapable of antigen processing, stimulated live influenza virus-reactive CD8 + T cell lines when loaded with NP-derived immunodominant peptides but not following loading with the whole NP molecule. Vaccines containing recombinant influenza NP might confer cross-protective immunity and could therefore be especially useful in cases of major epidemics or pandemics.