Antibody and cytotoxic T lymphocyte responses of humans to live and inactivated influenza vaccines.

The antibody and HLA-restricted virus-specific cytotoxic T lymphocyte (CTL) responses to influenza vaccine of 36 volunteers were analysed. Three vaccines were used: a live attenuated, and two types of inactivated, a whole virus and a purified surface antigen vaccine. Antibody to haemagglutinin (HA) was assayed using plaque neutralization, single-radial-haemolysis and haemagglutination-inhibition (HI) techniques. Antibodies to nucleoprotein and matrix antigens were also measured. Most of the volunteers had antibody responses to the HA in the inactivated vaccines which were detected by all three techniques. Nine of the twelve recipients of the live virus vaccine did not have an antibody response detected by the HI test, but four of these did have antibody responses when the plaque neutralization test was used. Single-radial-haemolysis was more sensitive than the HI test for detecting low levels of antibody, but the plaque neutralization test was the most sensitive for detecting low levels of antibody. Most volunteers had a rise in their HLA-restricted influenza-specific memory CTL response, but three recipients of live vaccine who did not have an antibody response by any technique also did not have an increase in their cytotoxic T cell activity. Three volunteers, two of whom had received live vaccine, had a positive CTL response without antibody response.