Parenteral influenza vaccination induces a rapid systemic and local immune response.

The kinetics of the local immune response in the upper respiratory tract to parenterally administered inactivated split trivalent influenza vaccine were examined in 19 healthy subjects. Influenza virus-specific antibody-secreting cells (ASC) could be detected as early as 2 days after vaccination in peripheral blood and tonsils, with a peak at approximately 1 week after vaccination and a decline to insignificant levels after 6 weeks. Circulating ASC produced IgG, IgA, and IgM, whereas ASC in tonsils produced mainly IgA and IgM. Influenza virus-specific antibodies were predominantly IgG and IgM in serum and IgA in oral fluid; they rose after 1 week and were elevated at 6 weeks. This may indicate a secretory involvement of the anti-influenza virus response in the upper respiratory tract. Parenteral influenza vaccination induced an immediate and significant immune response in both the upper respiratory tract and peripheral blood.