Cell-mediated immune response of human lymphocytes to influenza A/USSR (H1N1) virus infection.

Cell-mediated immunity to influenza A/USSR (H1N1) virus was assessed by measuring transformation response and interferon production by Ficoll-Hypaque-purified peripheral blood lymphocytes from children and adults. Lymphocyte transformation was found to be related to the individual's previous experience with H1N1 influenza virus. Lymphocyte cultures, obtained from adults who had their last contact with the H1N1 virus over 20 years ago, were able to transform when incubated with H1N1 influenza antigens. This response suggests that influenza virus can induced long-term cell-mediated immunity for periods of at least 20 years. Interferon produced by stimulated lymphocytes was found to be unrelated to previous contact with influenza H1N1 virus; seronegative as well as seropositive individuals were capable of producing interferon in response to viral antigens. The interferon produced was type I.