Serum neutralizing antibody and lymphocyte transformation responses after influenza B virus infections.

Serum neutralizing antibody and influenza B-specific lymphocyte blast transformation responses were measured in 110 adults and children after an influenza B outbreak. Serum neutralizing antibody and lymphocyte blast transformation responses were seen in 67 to 75% of adults and children recently infected (less than 1 year), but significant lymphocyte blast transformation responses were seen in only 25% of those whose infection was remote (greater than or equal to 3 years). The frequencies of influenza B-induced lymphocyte blast transformation and serum neutralizing antibody responses were similar in the adults and children with similar infection histories.