Lymphocyte cytotoxicity to influenza virus-infected cells: response to vaccination and virus infection.

Peripheral blood leukocytes obtained from volunteers at various times following influenza vaccine or live influenza virus infection were assayed for cytotoxicity against influenza virus-infected cells. Cytotoxicity was highest on days 3 and 7 following vaccination with commercial A/Port Chalmers/1/73 inactivated influenza virus vaccine. Maximal cytotoxicity was found 9 days after infection induced by intranasal inoculation of a strain of A/Scotland/840/74 influenza virus. Individuals naturally infected with A/Victoria/3/75 were also found to have elevated cytotoxicity approximately 1 week after onset of illness. Cytotoxicity levels decreased toward base line approximately 30 days after the virus exposure. The effector mechanism(s) responsible for the early, transient elevation in specific immune release to influenza virus-infected cells may be different from the antibody-dependent cell cytotoxicity demonstrated in the peripheral blood leukocytes from volunteers who had a remote experience with influenza virus.