Modulation of the lung local immune response by systemic immunization

The present study describes the respiratory immune response of mice to locally administered antigen, and the modulation of this response by systemic immunization. Intranasal immunization of mice with the A/PR/8/34 strain of influenza virus evoked local antibody response of the IgA type. The titer of the IgA antibodies declined to a nondetectable level in 40-50 days. If at that time a second intranasal dose was administered, a secondary IgA response was evoked. On the other hand, administration by the intramuscular route resulted in a mixed population of IgA and IgG antibodies. The relevance of this finding to problems of immunization against respiratory viral infections is discussed.